.. highlight:: text
.. _sec_cheatsheets:
###########
Cheatsheets
###########
.. _cheatsheet-wcs:
WCS
===
The `OGC Web Coverage Service (WCS) standard
<https://www.opengeospatial.org/standards/wcs>`__ defines support for modeling
and retrieval of geospatial data as *coverages* (e.g. sensor, image, or
statistics data).
WCS consists of a *Core* specification for basic operation support with regards
to coverage discovery and retreival, and various *Extension* specifications for
optional capabilities that a service could provide on offered coverage objects.
Core
----
The Core specification is agnostic of implementation details, hence, access
syntax and mechanics are defined by *protocol extensions*:
`KVP/GET <https://portal.opengeospatial.org/files/09-147r3>`__,
`XML/POST <https://portal.opengeospatial.org/files/09-148r1>`__, and
`XML/SOAP <https://portal.opengeospatial.org/files/09-149r1>`__. Rasdaman
supports all three, but further on the examples are in *KVP/GET* exclusively, as it
is the most straightforward way for constructing requests by appending a standard
`query string <https://en.wikipedia.org/wiki/Query_string>`__ to the
service endpoint URL. Commonly, for all operations the KVP/GET request will look
as follows: ::
http(s)://<endpoint url>?service=WCS
&version=2.0.1
&request=<operation>
&...
Three fundamental operations are defined by the Core:
- **GetCapabilities** - returns overal service information and a list of available
coverages; the request looks generally as above, with the `<operation>` being
GetCapabilities:
::
http(s)://<endpoint url>?service=WCS&version=2.0.1&request=GetCapabilities
Example:
http://ows.rasdaman.org/rasdaman/ows?service=WCS&version=2.0.1&request=GetCapabilities
- **DescribeCoverage** - detailed description of a specific coverage:
::
http(s)://<endpoint url>?service=WCS&version=2.0.1&request=DescribeCoverage
&coverageId=<coverage id>
Example:
http://ows.rasdaman.org/rasdaman/ows?service=WCS&version=2.0.1&request=DescribeCoverage&coverageId=AvgLandTemp
- **GetCoverage** - retreive a whole coverage, or arbitrarily restricted on any of
its axes whether by new lower/upper bounds (*trimming*) or at a single index
(*slicing*):
::
http(s)://<endpoint url>?service=WCS&version=2.0.1&request=GetCoverage
&coverageId=<coverage id>
[optional] &subset=<axis>(<lower>,<upper>)
[optional] &subset=<axis>(<index>)
[optional] &format=<mime type>
Example:
`http://ows.rasdaman.org/rasdaman/ows?service=WCS&version=2.0.1&request=GetCoverage&coverageId=AvgLandTemp&subset=Lon(-90.0,85.3)&subset=ansi("2014-10-01")&format=image/jpeg <http://ows.rasdaman.org/rasdaman/ows?service=WCS&version=2.0.1&request=GetCoverage&coverageId=AvgLandTemp&subset=Lon(-90.0,85.3)&subset=ansi("2014-10-01")&format=image/jpeg>`__
Updating
--------
The `Transaction extension (WCS-T)
<http://docs.opengeospatial.org/is/13-057r1/13-057r1.html>`__ specifies the
following operations for constructing, maintenance, and removal of coverages on
a server: *InsertCoverage*, *UpdateCoverage*, and *DeleteCoverage*.
Rasdaman provides the `wcst_import tool
<http://doc.rasdaman.org/05_geo-services-guide.html#data-import>`__ to simplify
the import of data into analysis-ready coverages (aka datacubes) by
generating WCS-T requests as instructed by a simple configuration file.
Processing
----------
The `Processing extension <https://portal.opengeospatial.org/files/08-059r4>`__
enables advanced analytics on coverages through `WCPS <cheatsheet-wcps>`__
queries. The request format is as follows: ::
http(s)://<endpoint url>?service=WCS&version=2.0.1&request=ProcessCoverages
&query=<wcps query>
e.g. calculate the average on the subset from the previous GetCoverage example:
`http://ows.rasdaman.org/rasdaman/ows?service=WCS&version=2.0.1&request=ProcessCoverages&query=for $c in (AvgLandTemp) return avg($c[Lon(-90.0:85.3), ansi("2014-10-01")]) <https://ows.rasdaman.org/rasdaman/ows?service=WCS&version=2.0.1&request=ProcessCoverages&query=for%20%24c%20in%20%28AvgLandTemp%29%20return%20avg%28%24c%5BLon%28-90.0%3A85.3%29%2C%20ansi%28%222014-10-01%22%29%5D%29%20>`__
Note that the query part (following the ``&query=`` parameter in the URL) needs
to be URL-encoded because it may contain characters that are not allowed in URLs.
This can be done online, e.g. with this `URLEncoder <https://www.urlencoder.io>`__,
or one can use a tool such as curl that does it automatically: ::
curl 'https://ows.rasdaman.org/rasdaman/ows?service=WCS&version=2.0.1&request=ProcessCoverages' \
-d 'query=for $c in (AvgLandTemp) return avg($c[Lon(-90.0:85.3), ansi("2014-10-01")])'
Range subsetting
----------------
The cell values of some coverages consist of multiple components (also known as
ranges, bands, channels, fields, attributes). The `Range subsetting extension
<https://portal.opengeospatial.org/files/12-040>`__ specifies the extraction
and/or recombination in possibly different order of one or more bands. This is
done by listing the wanted bands or band intervals; e.g
`AverageChlorophyllScaled` has Blue, Green, and Red bands and the following
recombines them into a Red, Green, Blue order:
`http://ows.rasdaman.org/rasdaman/ows?service=WCS&version=2.0.1&request=GetCoverage&coverageId=AverageChlorophyllScaled&format=image/png&subset=unix("2015-01-01")&rangesubset=Red,Green,Blue <http://ows.rasdaman.org/rasdaman/ows?service=WCS&version=2.0.1&request=GetCoverage&coverageId=AverageChlorophyllScaled&format=image/png&subset=unix("2015-01-01")&rangesubset=Red,Green,Blue>`__
Scaling
-------
Scaling up or down is a common operation supported by the `Scaling extension
<https://portal.opengeospatial.org/files/12-039>`__. An additional GetCoverage
parameter indicates the scale factor in several possible ways: as a single
number applying to all axes, multiple numbers applying to individual axes,
full target scale domain, or per-axis target scale domains. E.g. a single factor
to downscale all axes by 4x:
`http://ows.rasdaman.org/rasdaman/ows?service=WCS&version=2.0.1&request=GetCoverage&coverageId=AvgLandTemp&subset=ansi("2014-10-01")&format=image/jpeg&scaleFactor=0.25 <http://ows.rasdaman.org/rasdaman/ows?service=WCS&version=2.0.1&request=GetCoverage&coverageId=AvgLandTemp&subset=ansi("2014-10-01")&format=image/jpeg&scaleFactor=0.25>`__
Currently only nearest neighbour interpolation is supported for scaling.
Reprojection
------------
The `CRS extension <https://portal.opengeospatial.org/files/54209>`__ allows to
reproject a coverage before retreiving it. For example ``AverageChlorophyllScaled``
has native CRS EPSG:4326, and the following request will return the result in
EPSG:3857:
http://ows.rasdaman.org/rasdaman/ows?service=WCS&version=2.0.1&request=GetCoverage&coverageId=AverageChlorophyllScaled&format=image/png&subset=unix("2015-01-01")&outputCrs=http://ows.rasdaman.org/def/crs/EPSG/0/3857
or change the CRS in which subset or scale coordinates are specified:
http://ows.rasdaman.org/rasdaman/ows?service=WCS&version=2.0.1&request=GetCoverage&coverageId=AverageChlorophyllScaled&format=image/png&subset=Lon(0,10000000)&subset=Lat(0,20000000)&subset=unix(%222015-01-01%22)&subsettingCrs=http://ows.rasdaman.org/def/crs/EPSG/0/3857
The CRS in ``subsettingCrs`` / ``outputCrs`` can be specified in :ref:`these notations <crs-notation>`.
Interpolation
-------------
Reprojection (optionally with subsequent scaling) can be performed with various interpolation methods as
enabled by the `Interpolation extension
<https://portal.opengeospatial.org/files/12-049>`__:
http://ows.rasdaman.org/rasdaman/ows?service=WCS&version=2.0.1&request=GetCoverage&coverageId=mean_summer_airtemp&outputCrs=http://ows.rasdaman.org/def/crs/EPSG/0/3857&interpolation=http://www.opengis.net/def/interpolation/OGC/1.0/cubic
Rasdaman supports several interpolation methods as documented
:ref:`here <sec-geo-projection-interpolation>`.
.. _cheatsheet-wcps:
WCPS
====
The `OGC Web Coverage Processing Service (WCPS) standard
<https://www.opengeospatial.org/standards/wcps>`__ defines a
protocol-independent declarative query language for the extraction, processing,
and analysis of multi-dimensional coverages representing sensor, image, or
statistics data.
The overall execution model of WCPS queries is similar to XQuery FLOWR:
.. code-block:: rasql
for $covIter1 in (covName, ...),
$covIter2 in (covName, ...),
...
let $aliasVar1 := covExpr,
$aliasVar2 := covExpr,
...
where booleanExpr
return processingExpr
Any coverage listed in the WCS *GetCapabilities* response can be used in place
of ``covName``. Multiple ``$covIter`` essentially translate to nested loops.
For each iteration, the ``return`` clause is evaluated if the result of the
``where`` clause is ``true``. Coverage iterators and alias variables can be
freely used in where / return expressions.
Conforming WCPS queries can be submitted to rasdaman as `WCS ProcessCoverages
requests <https://portal.opengeospatial.org/files/08-059r4>`__, e.g: ::
http://localhost:8080/rasdaman/ows?service=WCS&version=2.0.1
&request=ProcessCoverages
&query=for $covIter in (covName) ...
The *WSClient* deployed with every rasdaman installation provides a convenient
console for interactively writing and executing WCPS queries: open
http://localhost:8080/rasdaman/ows in your Web browser and proceed to the
*ProcessCoverages* tab.
Operations can be categorized by the type of data they result in: scalar,
coverage, or metadata.
.. _wcps_scalar_operations:
Scalar operations
-----------------
- **Standard operations** applied on scalar operands return scalar results:
+------------------------------+---------------------------------------------------+
| Operation category | Operations |
+==============================+===================================================+
| Arithmetic | ``+ - * / abs round mod floor ceil`` |
+------------------------------+---------------------------------------------------+
| Exponential | ``exp log ln pow sqrt`` |
+------------------------------+---------------------------------------------------+
| Trigonometric | | ``sin cos tan sinh cosh tanh`` |
| | | ``arcsin arccos arctan atan2 arctan2`` |
+------------------------------+---------------------------------------------------+
| Comparison | ``> < >= <= = !=`` |
+------------------------------+---------------------------------------------------+
| Logical | ``and or xor not bit overlay`` |
+------------------------------+---------------------------------------------------+
| Select field from multiband | ``.`` |
| value | |
+------------------------------+---------------------------------------------------+
| Create multiband value | ``{ bandName: value; ..., bandName: value }`` |
+------------------------------+---------------------------------------------------+
| Type casting | ``(baseType) value`` |
| | |
| | | where baseType is one of: boolean, |
| | | [unsigned] char / short / int / long, |
| | | float, double, complex, complex2 |
+------------------------------+---------------------------------------------------+
- **Aggregation operations** summarize coverages into a scalar value.
+-----------------------+------------------------------------------------------+
| Aggregation type | Function / Expression |
+=======================+======================================================+
| Of numeric coverages | ``avg``, ``add`` (or alias ``sum``), ``min``, ``max``|
+-----------------------+------------------------------------------------------+
| Of boolean coverages | | ``count`` number of true values; |
| | | ``some``/``all`` = true if some/all values are true|
+-----------------------+------------------------------------------------------+
| General condenser | | ``condense`` *op* |
| | | ``over`` $iterVar axis(lo:hi), ... |
| | | [ ``where`` boolScalarExpr ] |
| | | ``using`` scalarExpr |
+-----------------------+------------------------------------------------------+
The *general condenser* aggregates values across an iteration domain with a condenser
operation *op* (one of ``+``, ``*``, ``max``, ``min``, ``and``, or ``or``).
For each coordinate in the iteration domain defined by the ``over`` clause, the
scalar expression in the ``using`` clause is evaluated and added to the final
aggregated result; the optional ``where`` clause allows to filter values from
the aggregation.
Coverage operations
-------------------
- **Standard operations** applied on coverage (or mixed coverage and scalar)
operands return coverage results. The operation is applied pair-wise on each
cell from the coverage operands, or on the scalars and each cell from the
coverage in case some of the operands are scalars. All coverage operands must
have matching domains and CRS.
- **Subsetting** allows to select a part of a coverage (or crop it to a smaller
domain): ::
covExpr[ axis1(lo:hi), axis2(slice), axis3:"crs"(...), ... ]
1. ``axis1`` in the result is reduced to span from coordinate ``lo`` to ``hi``.
Either or both ``lo`` and ``hi`` can be indicated as ``*``, corresponding to
the minimum or maximum bound of that axis.
2. ``axis2`` is restricted to the exact slice coordinate and removed from the
result.
3. ``axis3`` is subsetted in coordinates specified in the given ``crs``;
the CRS must be specified in one of :ref:`these formats <crs-notation>`. By
default coordinates must be given in the native CRS of ``C``.
- **Extend** is similar to subsetting but can be used to enlarge a coverage with
null values as well, i.e. lo and hi can extend beyond the min/max bounds of a
particular axis; only trimming is possible: ::
extend( covExpr, { axis1(lo:hi), axis2:crs(lo:hi), ... } )
.. _wcps-scale:
- **Scale** is like extend but it resamples the current coverage values to:
- Fit a new *grid* domain: ::
scale( covExpr, { axis1(lo:hi), axis2:"CRS:1"(lo:hi), ... } )
Note that ``axis1`` in this case should have a grid native CRS, such as
Index1D, while ``axis2`` may be any type of axis; in all cases ``lo`` and
``hi`` should be grid integer bounds.
- Fit the domain of another coverage: ::
scale( covExpr, { imageCrsDomain( $anotherCoverage ) } )
- Scale by a factor (factor > 1 for scaling up, 0 < factor < 1 for scaling down): ::
scale( covExpr, number )
- Scale by custom factor per axis: ::
scale( covExprs, { axi1(factor1), axis2(factor2), ... } )
Non-spatial axes which are omitted in the first and last variants will not be
scaled (details `here <wcps-optional-non-scaled-axes>`). If only one spatial
axis is specified, then the other spatial axis will be resampled so that the
original ratio is preserved(more details `here <wcps-auto-ratio-scaling>`).
Currently only nearest neighbour interpolation is supported for scaling.
- **Reproject** to a different CRS can be done with ``crsTransform``: ::
crsTransform( covExpr, { axisX:outputCRS, axisY:outputCRS }
[ , { interpolation } ]
[ , { axisLabelX:geoXRes, axisLabelY:geoYRes } ]
[ , { axisLabelX(lo:hi), axisLabelY(lo:hi)} |
{ domain(2Dcoverage) } ]
)
where the ``outputCrs`` can be specified in :ref:`these formats <crs-notation>`.
For example, the query below reprojects a 2D coverage to ``EPSG:4326`` CRS
with ``bilinear`` interpolation, target geo resolutions for ``Lat`` and
``Lon`` axes ``0.5`` and ``1 + the resolution of Lat axis in coverage $d``
respectively, and crops the result to the target geo domain
``[Lat(30.5:60.5), Lon(50.5:70.5)]``: ::
crsTransform($c,
{ Lat:"http://localhost:8080/rasdaman/def/crs/EPSG/0/4326",
Lon:"http://localhost:8080/rasdaman/def/crs/EPSG/0/4326" },
{ bilinear },
{ Lat:0.5, Lon:1 + domain($d, Lat).resolution },
{ Lat(30.5:60.5), Lon(50.5:70.5) }
)
.. _wcps-crstransform-shorthand:
Alternatively, a shorthand version can be used where the target CRS is applied
to both axes (instead of specifying it individually for each axis). A similar
example as above but with shorthand CRS notation and target geo domain that
matches the domain of coverage `$d`: ::
crsTransform($c,
"EPSG:4326",
{ bilinear },
{ Lat:0.5, Lon:1 + domain($d, Lat).resolution },
{ domain($d) }
)
For supported interpolation methods see the options for
:ref:`resampleAlg parameter <sec-geo-projection-interpolation>`.
- **Conditional evaluation** is possible with the ``switch`` statement:
.. code-block:: rasql
switch
case boolCovExpr return covExpr
case boolCovExpr return covExpr
...
default return covExpr
- **General coverage constructor** allows to create a coverage given a domain,
where for each coordinate in the domain the value is dynamically calculated
from a value expression which potentially references the iterator variables:
.. code-block:: rasql
coverage covName
over $iterVar axis(lo:hi), ...
values scalarExpr
Typically the iterator variable is iterated through a grid domain, e.g. by using the
``imageCrsdomain(coverageExpr, axisLabel)`` operator. However, iteration over
a geo domain is also supported with ``domain(coverageExpr, axisLabel)``.
Note that this feature is a non-standard extension that rasdaman provides
for convenience. For example, to create a 2D geo-referenced coverage with
``Lat`` and ``Lon`` axes, based on an existing geo-referenced coverage:
.. code-block:: rasql
for $c in (test_mean_summer_airtemp)
return
encode(
coverage targetCoverage
over $pLat Lat(domain($c[Lat(-30:-28.5)], Lat)),
$pLon Lon(domain($c[Lon(111.975:113.475)], Lon))
values $c[Lat($pLat), Lon($pLon)]
, "tiff")
- **General condenser on coverages** is same as the scalar general condenser,
except that in the ``using`` clause we have a coverage expression. The coverage
values produced in each iteration are cell-wise aggregated into a single
result coverage.
.. code-block:: rasql
condense op
over $iterVar axis(lo:hi), ...
[ where boolScalarExpr ]
values covExpr
- **Encode** allows to export coverages in a specified data format, e.g: ::
encode(covExpr, "image/jpeg")
WCPS supports ``application/gml+xml`` corresponding to an OGC WCS
``GetCoverage`` request. Many further formats are supported, see :ref:`here
<rasql-encode-function-data-format>` for details.
Atomic types
------------
The set of atomic types for Coverage range field data types according to
OGC WCPS standard. See :ref:`rasdaman atomic types <table-atomic-types>` for
comparison.
.. _table-atomic-coverage-range-field-types:
.. table:: Coverage atomic range field data types
+--------------------+------------+------------------------------------------+
| **type name** | **size** | **description** |
+====================+============+==========================================+
| ``boolean`` | 1 bit | true (nonzero value), false (zero value) |
+--------------------+------------+------------------------------------------+
| ``char`` | 8 bit | signed integer |
+--------------------+------------+------------------------------------------+
| ``unsigned char`` | 8 bit | unsigned integer |
+--------------------+------------+------------------------------------------+
| ``short`` | 16 bit | signed integer |
+--------------------+------------+------------------------------------------+
| ``unsigned short`` | 16 bit | unsigned integer |
+--------------------+------------+------------------------------------------+
| ``int`` | 32 bit | signed integer |
+--------------------+------------+------------------------------------------+
| ``unsigned int`` | 32 bit | unsigned integer |
+--------------------+------------+------------------------------------------+
| ``float`` | 32 bit | single precision floating point |
+--------------------+------------+------------------------------------------+
| ``double`` | 64 bit | double precision floating point |
+--------------------+------------+------------------------------------------+
| ``cint16`` | 32 bit | complex of 16 bit signed integers |
+--------------------+------------+------------------------------------------+
| ``cint32`` | 64 bit | complex of 32 bit signed integers |
+--------------------+------------+------------------------------------------+
| ``complex`` | 64 bit | single precision floating point complex |
+--------------------+------------+------------------------------------------+
| ``complex2`` | 128 bit | double precision floating point complex |
+--------------------+------------+------------------------------------------+
.. _wcps-metadata-operations:
Metadata operations
-------------------
Several functions allow to extract metadata information about a coverage ``C``:
+---------------------------+----------------------------------------------------+
| Metadata function | Result |
+===========================+====================================================+
| imageCrsDomain(C, a) | Grid (lo, hi) bounds for axis a |
+---------------------------+----------------------------------------------------+
| imageCrsDomain(C, a).x | Where x is one of ``lo`` or ``hi`` |
| | returning the lower or upper bounds respectively |
+---------------------------+----------------------------------------------------+
| domain(C, a, c) | Geo (lo, hi) bounds for axis a in CRS c |
| | returning the lower and upper bounds respectively |
+---------------------------+----------------------------------------------------+
| domain(C, a, c).x | Where x is one of ``lo`` or ``hi`` |
| | (returning the lower or upper bounds respectively) |
| | or ``resolution`` (returning the geo resolution of |
| | axis a) |
+---------------------------+----------------------------------------------------+
| domain(C, a) | Geo (lo, hi) bounds for axis a |
| | returning the lower and upper bounds respectively |
+---------------------------+----------------------------------------------------+
| domain(C, a).x | Where x is one of ``lo`` or ``hi`` |
| | returning the lower or upper bounds respectively |
+---------------------------+----------------------------------------------------+
| domain(C) | List of comma-separated axes and their bounds |
| | according to coverage's CRS orders respectively. |
| | Each list element contains an axis a |
| | with the lower and upper bounds in the axis CRS |
+---------------------------+----------------------------------------------------+
| crsSet(C) | Set of CRS identifiers |
+---------------------------+----------------------------------------------------+
| imageCrs(C) | Return the grid CRS (CRS:1) |
+---------------------------+----------------------------------------------------+
| nullSet(C) | Set of null values |
+---------------------------+----------------------------------------------------+
| cellCount(C) | Total number of grid pixels |
+---------------------------+----------------------------------------------------+
.. _wcps-comment-lines:
Comments
--------
WCPS supports SQL-like commenting styles:
- Single line comments start with ``--``. Any text following ``--``
to the end of the line will be ignored. Example:
.. code-block:: rasql
return encode($c, "image/png") -- Output encoded as 2D image
- Multi-line comments start with ``/*`` and end with ``*/``.
Any text between ``/*`` and ``*/`` are ignored. Example:
.. code-block:: rasql
/*
Output encoded as 2D image; result can be viewed in
Web browsers or image viewer tools.
*/
return encode($c, "image/png")
.. _cheatsheet-wms:
WMS
===
The `OGC Web Map Service (WMS) standard
<https://www.opengeospatial.org/standards/wms>`__ defines map portrayal on
geo-spatial data. In rasdaman, a WMS service can be enabled on any coverage,
including 3-D or higher dimensional; the latest 1.3.0 version is supported.
rasdaman supports two operations: *GetCapabilities*, *GetMap* from the standard.
We will not go into the details, as users do not normally hand-write WMS
requests, but let a client tool or library generate them instead. Check
the :ref:`cheatsheet-clients` section for some examples.
.. _cheatsheet-clients:
Clients
=======
.. _cheatsheet-wsclient:
Rasdaman WSClient
-----------------
WSClient is a web-client application to interact with WCS (version 2.0.1)
and WMS (version 1.3.0) compliant servers. Once rasdaman is installed it is
usually accessible at ``http://localhost:8080/rasdaman/ows``; a publicly
accessible example is available at http://ows.rasdaman.org/rasdaman/ows. The
client has three main tabs: ``OGC Web Coverage Service (WCS)``, ``OGC Web Map
Service (WMS)`` and ``Admin``. Further on, the functionality in each tab is
described in details.
WCS
^^^
There are sub-tabs for each of OGC WCS standard requests: GetCapabilities,
DescribeCoverage, GetCoverage, ProcessCoverages.
**GetCapabilities**
This is the default tab when accessing the WSClient. It lists all coverages
available at the specified WCS endpoint. Clicking on the ``Get Capabilities``
button will reload the coverages list. One can also search a coverage by typing
the first characters of its name in the text box. Clicking on a coverage name
will move to ``DescribeCoverage`` tab to view its metadata.
.. figure:: media/cheatsheets/wsclient_wcs-getcapabilities-tab-1.png
:align: center
List of coverages shown on the GetCapabilities tab.
If a coverage is geo-referenced, a checkbox will be visible in the ``Display
footprints`` column, allowing to view the coverage's geo bounding box (in
EPSG:4326) on the globe below.
.. figure:: media/cheatsheets/wsclient_wcs-getcapabilities-tab-2.jpg
:align: center
Selected coverage footprints shown on a globe.
..
-- rasdaman enterprise begin
.. _cheatsheet-wsclient-blacklist-coverages:
**[RE]** When logged in as petascope admin user, a ``Blacklisted`` column
will appear. A coverage can be hidden (blacklisted) from GetCapabilities
results by marking the checkbox, or shown (whitelisted) by unmarking the checkbox.
Clicking on ``Blacklist all`` or ``Whitelist all`` buttons will hide / show
all coverages.
.. figure:: media/cheatsheets/black_list_coverages.png
:align: center
Manage which coverages are shown to other users.
..
-- rasdaman enterprise end
At the bottom the metadata of the OGC WCS service endpoint are shown. These
metadata can be changed in the ``Admin -> OWS Metadata Management`` tab. Once
updated in the admin tab, click on ``Get Capabilities`` button to see the new
metadata.
.. figure:: media/cheatsheets/wsclient_wcs-getcapabilities-tab-3.png
:align: center
WCS service metadata.
**DescribeCoverage**
Here the full description of a selected coverage can be seen. One can type the
first few characters to search for a coverage id and click on ``Describe
Coverage`` button to view its OGC WCS metadata.
.. figure:: media/cheatsheets/wsclient_wcs-describecoverage-tab-1.png
:align: center
Showing full description of a coverage.
Once logged in as admin, it's possible to replace the metadata with one from a
valid XML or JSON file.
.. figure:: media/cheatsheets/wsclient_wcs-describecoverage-tab-2.png
:align: center
Updating the metadata of a coverage.
**GetCoverage**
Downloading coverage *data* can be done on this tab (or the next one,
ProcessCoverages). It's similiarly possible search for a coverage id in the text
box and click on ``Select Coverage`` button to view its boundaries. Depending on
the coverage dimension, one can do trim or slice subsets on the corresponding
axes to select an area of interest. The output format can be selected (provided
it supports the output dimension). Finally, clicking on ``Get Coverage`` button
will download the coverage.
.. figure:: media/cheatsheets/wsclient_wcs-getcoverage-tab-1.jpg
:align: center
Downloading a subset of a coverage, encoded in image/tiff.
In addition, further parameters can be specified as supported by the WCS
extensions, e.g. scaling factor, output CRS, subset of ranges (bands), etc.
**ProcessCoverages**
WCPS queries can be typed in a text box. Once ``Excute`` is clicked, the result
will be
- displayed on the output console if it's a scalar or the query was prefixed
with ``image>>`` (for 2D png/jpeg) or ``diagram>>`` for (1D csv/json);
- otherwise it will be downloaded.
.. figure:: media/cheatsheets/wsclient_wcs-processcoverages-tab-1.png
:align: center
Query and output areas on the ProcessCoverages tab.
**DeleteCoverage**
This tab allows to *delete* a specific coverage from the server. It is only
visible when logged in the ``Admin`` tab.
.. figure:: media/cheatsheets/wsclient_wcs-deletecoverage-tab-1.png
:align: center
Deleting coverage test_DaysPerMonth.
**InsertCoverage**
Similarly, this tab is only visible when logged in the ``Admin`` tab. To insert
a coverage, a URL pointing to a valid coverage definition according to the WCS-T
standard needs to be provided. Clicking on ``Insert Coverage`` button will
invoke the correct WCS-T request on the server.
.. figure:: media/cheatsheets/wsclient_wcs-insertcoverage-tab-1.png
:align: center
Inserting a coverage given a URL pointing to a valid GML document.
WMS
^^^
This tab contain sub-tabs which are related to the supported OGC WMS requests.
**GetCapabilities**
This tab lists the available layers on the specified server. To reload the list,
click on the ``Get Capabilities`` button. Clicking on a layer name will move to
``DescribeLayer`` tab to view its description.
.. figure:: media/cheatsheets/wsclient_wms-getcapabilities-tab-1.png
:align: center
List of layers shown on the GetCapabilities tab.
Similar to the WCS GetCapabilities tab, it's possible to search for layer names,
or show their footprints.
.. figure:: media/cheatsheets/wsclient_wms-getcapabilities-tab-2.jpg
:align: center
Selected layer footprints shown on a globe.
..
-- rasdaman enterprise begin
**[RE]** Similar to the WCS GetCapabilities tab, it's possible to
blacklist / whitelist layer(s).
.. figure:: media/cheatsheets/black_list_layers.png
:align: center
Manage which layers are shown to other users.
..
-- rasdaman enterprise end
**DescribeLayer**
Here the full description of a selected layer is shown. One can type the first
few characters to search for a layer name and click on ``Describe Layer`` button
to view its OGC WMS metadata.
.. figure:: media/cheatsheets/wsclient_wms-describelayer-tab-1.png
:align: center
Showing full description of a layer.
Depending on layer's dimension, one can click on ``show layer`` button and
interact with axes' sliders to view a layer's slice on the globe below. Click on
the ``hide layer`` button to hide the displayed layer on the globe.
.. figure:: media/cheatsheets/wsclient_wms-describelayer-tab-2.jpg
:align: center
Showing/hiding a layer on the map.
Once logged in as admin, managing WMS styles is possible on this tab.
To create a style, it is required to input various parameters along with
a rasql or WCPS query fragment, which are applied on every GetMap request
if the style is active. Afterwards, click on ``Insert Style`` to insert
a new style or ``Update Style`` to update an existing style of the current
selected layer. One can also delete an existing style by clicking on
the ``Delete`` button corresponding to a style name.
.. figure:: media/cheatsheets/wsclient_wms-describelayer-tab-3.png
:align: center
Style management on the DescribeLayer tab.
Finally, once logged in as admin, managing downscaled collection levels
of a WMS layer is also possible on this tab. To create a new level,
it is required to input level parameter (positive number). Afterwards,
click on ``Insert Level`` to insert a new downscaled collection level
of the current selected layer. One can also delete an existing level
by clicking on the ``Delete`` button corresponding to a downscaled
collection level.
.. figure:: media/cheatsheets/wsclient_wms-describelayer-tab-4.png
:align: center
Downscaled collection level management on the DescribeLayer tab.
`NASA WebWorldWind <https://worldwind.arc.nasa.gov/web/>`__
-----------------------------------------------------------
- Simple example to setup a web page with a map from a WMS server using WebWorldWind:
.. code-block:: html
<html>
<head>
<script src="https://files.worldwind.arc.nasa.gov/artifactory/web/0.9.0/worldwind.min.js"></script>
<script>
document.addEventListener("DOMContentLoaded", function(event) {
WorldWind.Logger.setLoggingLevel(WorldWind.Logger.LEVEL_WARNING);
var wwd = new WorldWind.WorldWindow("canvasOne");
var layers = [{
layer: new WorldWind.BingRoadsLayer(null),
enabled: true
}, {
layer: new WorldWind.CoordinatesDisplayLayer(wwd),
enabled: true
}, {
layer: new WorldWind.ViewControlsLayer(wwd),
enabled: true
}];
for (var l = 0; l < layers.length; l++) {
wwd.addLayer(layers[l].layer);
}
var layerNamesToRequest = ["AvgTemperatureColorScaled"];
var config = {
title: "AvgTemperatureColorScaled", version: "1.3.0",
service: "http://ows.rasdaman.org/rasdaman/ows",
layerNames: layerNamesToRequest,
// min Lat, max Lat, min Long, max Long of the requesting layer
sector: new WorldWind.Sector(-90, 90, -180, 180),
levelZeroDelta: new WorldWind.Location(36, 36),
numLevels: 15, format: "image/png", styleNames: "", size: 256
};
var wmsLayer = new WorldWind.WmsLayer(config);
wmsLayer.enabled = true;
wwd.addLayer(wmsLayer);
});
</script>
</head>
<body>
<canvas id="canvasOne" style="width: 100%; height: 100%;"> </canvas>
</body>
</html>
- Simple example to setup a web page with a map from a WMTS server using WebWorldWind:
.. code-block:: html
<html>
<head>
<script src="https://files.worldwind.arc.nasa.gov/artifactory/web/0.9.0/worldwind.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js" type="text/javascript"></script>
</head>
<body>
<canvas id="canvasOne" style="width: 100%; height: 100%;"> </canvas>
<script>
var wwd = new WorldWind.WorldWindow("canvasOne");
document.addEventListener("DOMContentLoaded", function(event) {
WorldWind.Logger.setLoggingLevel(WorldWind.Logger.LEVEL_WARNING);
var layers = [{
layer: new WorldWind.BingRoadsLayer(null),
enabled: true
}, {
layer: new WorldWind.CoordinatesDisplayLayer(wwd),
enabled: true
}, {
layer: new WorldWind.ViewControlsLayer(wwd),
enabled: true
}];
for (var l = 0; l < layers.length; l++) {
wwd.addLayer(layers[l].layer);
}
});
// Web Map Tiling Service information from
var serviceAddress = "http://localhost:8080/rasdaman/ows?service=WMTS&version=1.0.0&request=GetCapabilities";
// Layer displaying Gridded Population of the World density forecast
var layerIdentifier = "test_world_map";
// Called asynchronously to parse and create the WMTS layer
var createLayer = function(xmlDom) {
// Create a WmtsCapabilities object from the XML DOM
var wmtsCapabilities = new WorldWind.WmtsCapabilities(xmlDom);
// Retrieve a WmtsLayerCapabilities object by the desired layer name
var wmtsLayerCapabilities = wmtsCapabilities.getLayer(layerIdentifier);
// Form a configuration object from the WmtsLayerCapabilities object
var wmtsConfig = WorldWind.WmtsLayer.formLayerConfiguration(wmtsLayerCapabilities);
// Create the WMTS Layer from the configuration object
var wmtsLayer = new WorldWind.WmtsLayer(wmtsConfig);
// Add the layers to WorldWind and update the layer manager
wwd.addLayer(wmtsLayer);
};
// Called if an error occurs during WMTS Capabilities document retrieval
var logError = function(jqXhr, text, exception) {
console.log("There was a failure retrieving the capabilities document: " + text + " exception: " + exception);
};
$.get(serviceAddress).done(createLayer).fail(logError);
</script>
</body>
</html>
Python / Jupter Notebook
------------------------
OWSLib
^^^^^^
`OWSLib <https://geopython.github.io/OWSLib/>`__ is a Python package that helps
with programming clients for OGC services such as WCS, WCPS, or WMS. To install
it follow the official `installation instructions
<https://geopython.github.io/OWSLib/#installation>`__. Example usage for WCS
follows below.
.. code-block:: python
>>> # Import OWSLib in Python once installed
... from owslib.wcs import WebCoverageService
>>> # Create coverage object
... my_wcs = WebCoverageService('http://ows.rasdaman.org/rasdaman/ows',
... version='2.0.1')
>>> # Get list of coverages
... print my_wcs.contents.keys()
['RadianceColor', 'test_irr_cube_2', 'test_mean_summer_airtemp',
'test_double_1d', 'INSPIRE_EL', 'AverageChlorophyllScaled', 'INSPIRE_OI_RGB',
'Temperature4D', 'INSPIRE_OI_IR', 'visible_human', 'INSPIRE_WS_LC',
'meris_lai', 'climate_earth', 'mean_summer_airtemp', 'multiband',
'ls8_coastal_aerosol', 'NN3_3', 'NN3_2', 'NN3_1', 'NN3_4',
'AvgTemperatureColorScaled', 'AverageChloroColorScaled', 'lena',
'Germany_DTM', 'climate_cloud', 'FiLCCoverageBit', 'AverageChloroColor',
'LandsatMultiBand', 'RadianceColorScaled', 'AvgLandTemp', 'NIR', 'BlueMarbleCov']
>>> # Get geo-bounding boxes and native CRS
... my_wcs.contents['AverageChlorophyllScaled'].boundingboxes
[{'nativeSrs': 'http://ows.rasdaman.org/def/crs-compound?
1=http://ows.rasdaman.org/def/crs/EPSG/0/4326&
2=http://ows.rasdaman.org/def/crs/OGC/0/UnixTime',
'bbox': (-90.0, -180.0, 90.0, 180.0)}]
>>> # Get axis labels
... my_wcs.contents['AverageChlorophyllScaled'].grid.axislabels
['Lat', 'Long', 'unix']
>>> # Get dimension
... my_wcs.contents['AverageChlorophyllScaled'].grid.dimension
3
>>> # Get grid lower and upper bounds
... my_wcs.contents['AverageChlorophyllScaled'].grid.lowlimits
['0', '0', '0']
>>> my_wcs.contents['AverageChlorophyllScaled'].grid.highlimits
['119', '239', '5']
>>> # Get offset vectors for geo axes
... my_wcs.contents['AverageChlorophyllScaled'].grid.offsetvectors
[['-1.5', '0', '0'], ['0', '1.5', '0'], ['0', '0', '1']]
>>> # For coverage with time axis get the date time values
... my_wcs.contents['AverageChlorophyllScaled'].timepositions
[datetime.datetime(2015, 1, 1, 0, 0), datetime.datetime(2015, 2, 1, 0, 0),
datetime.datetime(2015, 3, 1, 0, 0), datetime.datetime(2015, 4, 1, 0, 0),
datetime.datetime(2015, 5, 1, 0, 0), datetime.datetime(2015, 7, 1, 0, 0)]
rasdapy3
^^^^^^^^
`rasdapy3 <https://pypi.org/project/rasdapy3/>`__ is a client API for rasdaman
that enables building and executing rasql queries within python.
Best practice code snippets are also provided.
wcps_rasdaman.py
^^^^^^^^^^^^^^^^
`wcps_rasdaman.py <https://gitlab.inf.unibz.it/SInCohMap/RoundRobinTutorials/blob/master/wcps_rasdaman.py>`__
is a python client which sends a WCPS query to a rasdaman server and wraps the response for further use
depending on the response format chosen in the query.
.. _cheatsheets-access-from-r:
Access from R
-------------
Accessing rasdaman from R is possible in three ways right now:
- :ref:`RRasdaman <sec-rrasdaman-install>` enables connecting to rasdaman,
executing rasql queries, and retreiving results.
Note that it is *only* for rasql queries, so it is not suitable for querying geo-referenced coverages.
- `CubeR <https://mattia6690.github.io/CubeR/>`__ allows convenient execution
of WCPS queries directly from R. Check also this accompanying `presentation
<https://sao.eurac.edu/wp-content/uploads/2018/07/RossiEtAl_EGU2018_PICO_DataCubes.compressed.pdf>`__.
- `ows4R <https://cran.r-project.org/web/packages/ows4R/>`__ provides an interface to OGC Web services,
including Web Coverage Service (WCS) which is supported by rasdaman.
Steps to install ``ows4R`` package and its dependencies on Ubuntu 20.04:
.. code-block:: shell
sudo apt-get install libsodium-dev libudunits2-dev
sudo R
install.packages("sodium")
install.packages("keyring")
install.packages("geometa")
install.packages("units")
install.packages("sf")
install.packages("ows4R")
For more details check the `ows4R WCS tutorial <https://eblondel.github.io/ows4R/articles/wcs.html>`__.
`OpenLayers <https://openlayers.org/>`__
----------------------------------------
Simple example to setup a web page with a map from a WMS server using OpenLayers:
.. code-block:: html
<html>
<head>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/openlayers/3.8.2/ol.css"></link>
<script src="https://cdnjs.cloudflare.com/ajax/libs/openlayers/3.8.2/ol.js"></script>
<script>
document.addEventListener("DOMContentLoaded", function(event) {
var layers = [
new ol.layer.Tile({
source: new ol.source.TileWMS({
url: "https://ahocevar.com/geoserver/wms",
params: {'LAYERS': 'ne:NE1_HR_LC_SR_W_DR'}
})
}),
new ol.layer.Tile({
source: new ol.source.TileWMS({
url: "http://ows.rasdaman.org/rasdaman/ows",
params: {'LAYERS': 'AvgTemperatureColorScaled'}
})
})
];
var map = new ol.Map({
layers: layers,
target: 'map',
view: new ol.View({
center: [7.5, 53.15178], projection : "EPSG:4326", zoom: 6
})
});
});
</script>
</head>
<body>
<div id="map" style="width: 100%; height: 95vh"> </div>
</body>
</html>
`Leaflet <https://leafletjs.com/examples/wms/wms.html>`__
---------------------------------------------------------
Simple example to setup a web page with a map from a WMS server using Leaflet:
.. code-block:: html
<html>
<head>
<link rel="stylesheet" href="https://unpkg.com/leaflet@1.6.0/dist/leaflet.css"/>
<script src="https://unpkg.com/leaflet@1.6.0/dist/leaflet.js"></script>
<script>
document.addEventListener("DOMContentLoaded", function(event) {
var map = new L.Map('map', {
center: new L.LatLng(40, 52),
zoom: 3, attributionControl: true, zoomControl: true, minZoom: 2
});
var wmsLayer = L.tileLayer.wms("http://ows.rasdaman.org/rasdaman/ows", {
version: '1.3.0', layers: 'AvgTemperatureColorScaled', format: 'image/png'
});
map.addLayer(wmsLayer);
});
</script>
</head>
<body>
<div id="map" style="width: 100%; height: 100%;"> </div>
</body>
</html>
`ArcGIS <https://www.esri.com/en-us/arcgis/products/arcgis-online/overview>`__
------------------------------------------------------------------------------
`ArcGIS Online
<https://www.esri.com/en-us/arcgis/products/arcgis-online/overview>`__ does not
directly allow accessing 3rd party services, however such a service can be
connected into some existing ArcGIS Server instance. In the following, the
`ArcGIS Online documentation
<https://doc.arcgis.com/en/arcgis-online/manage-data/add-item-from-url.htm>`__
is cited.
OGC WMS or WMTS layers can be added to ArcGIS Online `to maps
<https://doc.arcgis.com/en/arcgis-online/reference/ogc.htm#ESRI_SECTION1_CE375065C52946C783C460BE1618B721>`__
in Map Viewer or Map Viewer Classic `to scenes
<https://doc.arcgis.com/en/arcgis-online/create-maps/add-layers-to-scene.htm>`__
in Scene Viewer, and `as items
<https://doc.arcgis.com/en/arcgis-online/manage-data/add-item-from-url.htm>`__
to ArcGIS.
`QGIS <https://docs.qgis.org/3.4/en/docs/user_manual/working_with_ogc/ogc_client_support.html#wms-wmts-client>`__
-----------------------------------------------------------------------------------------------------------------
Command-line tools
------------------
It's straightforward to make individual OGC WCS / WCPS / WMS requests from the
terminal. Examples with ``curl`` follow.
- Make a GetCapabilities request:
.. code-block:: shell
curl "http://ows.rasdaman.org/rasdaman/ows\
?service=WCS&version=2.0.1&request=GetCapabilities"
- Execute a WCPS query with a ProcessCoverages request:
.. code-block:: shell
curl "http://ows.rasdaman.org/rasdaman/ows" -o test.png --data-urlencode \
'service=WCS&version=2.0.1&request=ProcessCoverages&query=\
for c in (mean_summer_airtemp) return encode(c, "png")'
- Upload files to be processed with ``decode()`` operator, see :ref:`here <positional_parameters_in_wcps>`.
- When the server requires basic authentication for a request, the rasdaman
user credentials can be specified with the ``--user`` option, e.g.
.. code-block:: shell
curl --user "rasadmin:rasadmin" \
"http://localhost:8080/rasdaman/ows?
service=WCS&version=2.0.1&request=DeleteCoverage&coverageId=test_coverage"
Rasql Web Console
-----------------
The rasql web console is installed by rasdaman in ``$RMANHOME/share/rasdaman/www/rasql-web-console``.
It requires petascope to be running in the background in order to execute queries.
Various widgets are available, with the most commonly-used being:
- ``image`` to visualize a 2D image result, e.g. ``image>>select encode(..., "jpeg") from ...``
- ``diagram`` on csv encoded data, e.g. ``diagram(type=area,width=300)>>select encode(..., "csv") from ...``
- ``text`` to visualize a text result, e.g. ``text>>select dbinfo(...) from ...``
Without using a widget the result is downloaded:
.. figure:: media/cheatsheets/rasql-web-console-example.png
:align: center
Example of a 2D image result.
WCPS QGIS Plugin
----------------
This plugin allows sending datacube queries as per OGC Web Coverage Processing
Service (WCPS) to a server and displaying the results directly in QGIS.
Installation
^^^^^^^^^^^^
1. On the terminal, install the ``xmltodict`` dependency required by the plugin:
.. code-block:: shell
pip3 install xmltodict
2. Select QGIS menu ``Plugins`` → ``Manage and Install Plugins``, then search for
``wcps``; this should return the plugin ``WCPS datacube query``;
3. Click ``Install Plugin`` to install it in QGIS;
4. Now you can access the plug-in via the QGIS Menu ``Plugins`` →
``WcpsClient1`` → ``WCPS 1.0 Client``, or click on the new cube icon on the
toolbar.
.. figure:: media/cheatsheets/install_plugin.png
:align: center
Server configuration
^^^^^^^^^^^^^^^^^^^^
To start working with the plugin, you need to add a server to which requests
will be sent. To do this, click on the ``New`` button and specify a name/link
to the server, then click ``OK``. After adding the server data, select it from
the available ones in the drop-down list.
.. figure:: media/cheatsheets/server_tab.jpg
:align: center
If the server requires authentication to send requests, you can specify
credentials in the ``Username`` and ``Password`` fields.
After specifying all the necessary data, click the ``Connect`` button to connect
to the server. This should show a list of all available coverages on the
``Coverage List`` tab.
.. figure:: media/cheatsheets/list_of_all_coverages.jpg
:align: center
Query writing
^^^^^^^^^^^^^
You can create a query using the ``WCPS Query Editor`` and ``Visual Query
Editor`` tabs.
.. figure:: media/cheatsheets/query_editor_tab.jpg
:align: center
On the ``WCPS Query Editor`` tab the query is entered as free text. Queries can
be persisted and loaded with the ``Store Query`` and ``Load Query`` buttons. To
submit a query to the server, click the ``Submit`` button. If the request is
successful, a window for choosing further actions with the result will be
shown.
.. figure:: media/cheatsheets/result_of_evaluating_query.jpg
:align: center
.. _qgis_result_actions:
- To save the query result click the ``Save result`` button
- To show the file in QGIS click the ``Show result in QGIS layer`` button
- To save and show the file in QGIS click the ``Save and show result in QGIS
layer`` button.
- To ignore the result click the ``Discard result`` button
.. figure:: media/cheatsheets/visual_query_tab.jpg
:align: center
The ``Visual Query Editor`` tab allows to construct the high-level structure of
the query with buttons and inputs with support for code-completion.
To add datacubes over which you will iterate in the for part, click the ``Add
datacube`` button, which allows to select datacubes from the list of available
ones on the server and enter a variable that will be used to refer to the
datacube in the query body.
.. figure:: media/cheatsheets/add_coverages.jpg
:align: center
To remove datacubes from the list, select them in the ``Selected Datacubes``
list and click the ``Delete Datacube`` button.
.. figure:: media/cheatsheets/coverage_delete.jpg
:align: center
To add multiple variables for iteration click on the Add datacubes button
several times. To add filtering to your query (a WHERE clause) click on the
``Set filter condition`` button and enter the necessary conditions.
The ``Result expression`` field should contain the processing expression that
should be calculated as a result. Select the format in which the result will be
encoded in the drop-down list; to specify a custom format, select custom from
the drop-down list and write it in the corresponding field.
.. figure:: media/cheatsheets/coverage_delete.jpg
:align: center
You can also specify the format parameters by clicking on the
``Format Parameters`` button and entering them in a special field in the window
that opens. After specifying all the required data, click the Evaluate button to
send the generated query. If the query is successful, you will see a window
for choosing further actions with the results of the request, which was
described previously :ref:`here <qgis_result_actions>`.