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WebMapViewer FAQ Help

This FAQ groups common questions about the WebMapViewer, SSEs' cartographic map display, and provides answers for them.

Questions

Answers

Question: When I try to add an OGC Web Service to the WebMapViewer, I get the message back saying that the service cannot be added. What’s wrong?
Answer 
  • Check the accessibility of the service from outside your organisation (port that may be blocked) - You can use the WMS, WFS and WCS test tools for this.
  • Validate the capabilities XML.
  • Verify that you have actually declared information layers (WMS layers, WFS FeatureTypes and WCS Coverages) inside these capabilities.
  • Ensure that within the capabilities XML the connection points are properly set to external accessible URLs - not localhost, …
  • In case of WFS validate the DescribeFeatureType XML and ensure that it contains the correct information
  • In case of WCS validate the DescribeCoverage XML and ensure that it contains the correct information
  • In case of WFS bear in mind the default filter criteria that you may have set and the fact that the max number of features is limited
  • In case of WCS verify that your coverage files (GeoTIFF) are correct and can be read by the GDAL software.

Question: When I try to add Service Result GML, I get a "No features added" message, what is wrong?
Answer 
  • If you are providing an HTTP URL to a file, check that it is correct, on port 80 and accessible from the SSE Portal;
  • Check that the GML is correct XML: verify well-formedness and validate it
Question: When I try to add Service Result GML, nothing happens or the points are displayed in the wrong place?
Answer 
  • If your GML is GML2 compliant, the WebMapViewer will assume coordinates are in X,Y order meaning longitude, latitude.
  • If you have GML3, we will assume it to be lat/lon. Note that the GML file format counts, not the AOI GML version setting in the configurator
Question: When I try to add Service Result shape files, the files are not shown, or I cannot select them?
Answer 
  • Ensure that you follow the constraints laid out within the SSE ICD about which attributes should be present, how the file needs to be zipped, ...

  • Ensure that the URL you provide is correct.

  • Ensure that the file does not exceed the file size limitation.
Question: I do not like the colours of the features on the map can I influence those?
Answer 
  • Yes you can - you can upload an OGC Styled Layer Descriptor (SLD) file.
  • You can either base yourself on examples or alternatively use an SLD editor to create them.
Question: I am using my own WMS server which does not allow to create transparent images. Is there a way to show these layers in a transparent manner anyway?
Answer 

Yes, the WebMapViewer can make your layer transparent. In order to do this, you need to specify the following parameters when adding the layer. Either by including them as KeyValuePairs in the URL or as KeyValuePairs in the parameters text box within the "Add Layer Window".

  • TRANSPARENT=TRUE: signifying that you want the WMS layers to be transparent

FORMAT=image/jpeg: if transparent is set to true and you select jpeg as image format which does not allow transparency, the WebMapViewer recognises that it should make the image transparent. If you select a transparent image format, the WebMapViewer ignores this parameter as it expects he server to render the image transparent.

  • BGCOLOR=0xFFFFFF&: the base colour to be set transparent.
  • BGCOLOR_TOLERANCE=202020: This a proprietary parameter only understood by the SSE WebMapViewer. It specifies the tolerance that should be applied on the backgroundcolours' channels (Red,Green, Blue) when deciding upon the colour range that is to be set to transparent.


Question: Is there a way to add features to the WebMapViewer from within the Service stylesheets?
Answer 

Yes you can.
Some aspects of the webMapViewer can be controlled by a Javascript API. One of the functions that exists, "updateFeatures", allows you to add Service Result and Area Of Interest GML and WFS features (from a String or from a file via a URL) to the map.

The updateFeatures function parameters are:
- aoiFeaturesURL String: URL to a valid AOI GML file
- aoiFeaturesString String: a valid AOI GML String
- srFeaturesURL String: URL to a valid SR GML file
- srFeaturesString String: a valid SR GML String
- wfsFeaturesURL String: a pipe-separated string consisting of the WFS base URL, the FeatureType and a Query Statament
- clearAOI Boolean value to indicate whether all existing AOI should be removed
- clearSR Boolean value to indicate whether all existing AOI should be removed
- clearWFS Boolean value to indicate whether all existing AOI should be removed

Question: I have added a WFS Feature Layer to my map, when I use the Toolbar button with the I icon, and then click on the map, I do not get any meaningful information back?
Answer 

The "I" Toolbar button executes a WMS GetFeatureInformation Request and is only to be used for WMS Layers.
If you are dealing with a WFS Layer, you should use the button with the "?" instead.

Question: Can you provide an example of how to configure the animation controls for a WMS with a Time dimension.
Answer 

The procedure is the following

1) Go to the service registration wizard and select WMS
2) In the WebMapViewer configuration window, click on the Load button located underneath the map in the bottom right corner.
3) Click on the plus icon in the layer manager
4) In the window that appears select "Define a server yourself" and paste the following URL http://mesonet.agron.iastate.edu/cgi-bin/wms/nexrad/n0r.cgi?SERVICE=WMS&request=GetCapabilities and click on OK.
5) Subsequently select the "NexRad BAse Ref WMS-T layer". You will now see a map layer appearing over the US
6) In the layer manager window, select the NexRad Layer and then click on the layer configuration button (This is the "wheel" button located at the bottom of the layer manager).
7) In the window that appears, check the "show animation controls" checkbox.
8) Save the WebMapViewer Configuration by clicking on the "Save button" underneath the map.
9) Continue with the service registration.
10) When you start the service, the WebMapViewer will appear. Subsequently select the NexRad Layer in the layer manager and the animation controls will appear.

You can see the result at http://services-test.eoportal.org/portal/order/PrepareOperation.do?serviceId=F3807282&operation=Search .