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11 votes
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When validating geometries, what are "Nested shells"?

A Nested Shell is a polygon on top of another polygon. Image source
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11 votes
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Is srsName of "EPSG:4326" spec compliant in GML 3.1 / 3.2?

Yes, srsName="EPSG:abcd" is GML-3 compliant but only in an application context where EPSG:abcd points to a CRS definition. As of 2013, OGC best practice (documented here) is to use http URIs of the ...
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10 votes

Why do single-part WKT polygon vertices require double parentheses?

It is because polygons can have multiple rings in them, the exterior and a list of interior rings or holes. To save parsers having to guess if there are holes by the number of brackets there are ...
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10 votes

Why do single-part WKT polygon vertices require double parentheses?

@user30184 already gave the short answer in the comments here. For a longer answer, one needs to look to the Simple Feature Access - Part 1: Common Architecture | OGC standard. The Well-known Text (...
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9 votes

How are ESRI WKT projections different from OGC WKT projections?

You've caught a lot of the differences. Esri never adopted the WKIDs for the map projection algorithms or parameter names so those are all different. We didn't agree with how carefully defined the ...
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  • 18.2k
8 votes
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Is GeoJSON an OGC format

No, GeoJSON is not an OGC standard: IETF Geographic JSON Working Group The Internet Engineering Task Force, in conjunction with the original specification authors, has formed the Geographic JSON WG ...
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  • 3,485
7 votes

REST API for OGC standards

As @PolyGeo suggested, I am converting my comments into an answer. The answer is split into three parts to broadly reflect the three comments I made. Part 1 Roy Fielding's dissertation that ...
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7 votes
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Validity standard for GeoJSON polygons?

Polygons are not simple to handle and there are more than two worlds. I recommend to read this article "About Invalid, Valid and Clean Polygons" http://www.springer.com/%3FSGWID%3D5-102-45-...
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7 votes
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See WFS or WMS corresponding full http request in QGIS when a layer was added from any of these services

If you have QGIS 3.14, press F12. Otherwise install the Network logger plugin.
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6 votes
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How are ESRI WKT projections different from OGC WKT projections?

I don't have such a list, but going through the GDAL code will guide you: https://svn.osgeo.org/gdal/trunk/autotest/osr/osr_esri.py https://trac.osgeo.org/gdal/browser/trunk/gdal/ogr/ogr_srs_esri....
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  • 75.1k
6 votes
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Is there a common standard for how GIS information is displayed?

There is SLD (Styled Layer Descriptor), which I think is mainly used in OpenGIS environments. ArcGIS might have some support for it, but I have never pursued that option myself.
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  • 4,173
6 votes
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Relationship between WMS styles and layers parameters for GetMap request in WMS 1.3.0?

The WMS 1.3.0 specification says in section 7.3.3.4: The mandatory STYLES parameter lists the style in which each layer is to be rendered. The value of the STYLES parameter is a comma-separated ...
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  • 1,738
6 votes
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Geometry data type Binary storage description

WKB presentation is defined in the OGC standards for Simple Feature Access https://www.ogc.org/standards/sfa. The details are in the document https://portal.ogc.org/files/?artifact_id=25355, Chapter 8....
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5 votes
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Is there free WFS 2.0 client?

The QGIS client plugin is a good one - I was able to access the features of WFS without issue. ArcGIS has an interoperability connections feature that must be enabled by a user with administrator ...
5 votes
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Differences between OGC and ISO WKT/WKB specification?

If you are working with geometry types beyond the usual point/line/polygon/collection or are working with more than 2 dimensions, then yes, get the ISO spec. Otherwise, no. Also get the old OGC ...
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5 votes

INSPIRE, GEOSS and OGC

The Open Geospatial Consortium (OGC) exists to define interface standards such as the Web Mapping Service (WMS) standard, or Web Feature Service (WFS) standard. These are standards that define how ...
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5 votes
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What's the difference between coordinateDimension and spatialDimension?

dimension(): refers to the topological dimension (i.e. point/line/area) coordinateDimension(): returns the dimension of the tuple as given (as statet in the OP) spatialDimension(): returns the ...
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  • 899
4 votes
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Number of zoom levels in WMS?

There is no concept of zoom "levels" in the WMS specification, as there is for an XYZ/TMS. Rather, your WMS requests just use a bounding box which determines map scale.
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4 votes
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Using CQL for a poor man's temporal filter on a server offering only WFS 1.1.0

Note only a GeoServer based WFS will understand a CQL filter, you can and should use an OGC Filter to achieve this effect too. You can use one (or more) of the ECQL temporal filters for this. I would ...
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  • 75.1k
4 votes
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Seeking open vector format for long term GIS data storage in off-line repositories?

In my opinion, Shapefile is a good choice, but it has many limitations for historical reasons. For example, a single shapefile cannot be greater than 2GB, etc. You have to decide whether to commit to ...
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4 votes

Failure to Add Layer from a WFS Provider QGIS 2.18.10

It may be an issue with your network or a temporary issue with the server, it works for me. I added http://ide.igvsb.gob.ve/geoserver/escala250000/wfs/?VERSION=1.0.0 to as the WFS url and then added ...
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  • 75.1k
4 votes
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How to SortBy a GetFeature WFS request by FeatureId (fid) in XML?

That is not supposed to work. SortBy is defined in the WFS 1.1.0 standard as The SORTBY parameter is used to specify a list of property names whose values should be used to order (upon ...
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  • 52.5k
4 votes

Feature Identifiers in WFS

After a bit of digging I found that gml:id is of type xml:ID: For both attributes and simple element content, the lexical domain of these datatypes is the lexical domain of XML nonqualified names (xs:...
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  • 75.1k
4 votes

Feature Identifiers in WFS

Rules for gml:id come from the GML standard. This is about GML 3.2 7.2.4.5 id The attribute gml:id supports provision of a handle for the XML element representing a GML object. Its use is mandatory ...
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4 votes
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Limit access to WMS service after number of requests

WMS standard defines only how the service should work and it is assumed that every request will get an answer. How to limit the usage of the service is not in the scope of the standard. I agree with @...
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3 votes

Is there an open standard for raster information?

Good question and not one I've really given thought to before. This might be the sort of thing you're interested in: Some searching show's that there's ISO19123:2005 - "Geographic information -- ...
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  • 6,591
3 votes
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Mbtile To Geopackage and vice versa

Doing such a conversion (or supporting both in the same file) was a goal of GeoPackage. It isn't just a schema change though, because of different Y order conventions - you need to use a view to ...
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  • 12.5k
3 votes

Is there free WFS 2.0 client?

QGIS 2.16 brings an overhaul of the WFS provider, including WFS 1.1 and 2.0 support Source: http://qgis.org/pl/site/forusers/visualchangelog216/index.html#id96
3 votes

Is GeoJSON an OGC format

OGC Standards are listed on the OGC Standards page. As you will see GeoJSON is not amongst them.
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3 votes

Server (MapServer) does not support the gml coverage

It would help a lot to mention where to get the test suite https://github.com/opengeospatial/ets-wcs20 and which exact test you run, and also study the test suite and try to analyze what is probably ...
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