Gridlayer with domain not in geometries: projection is recognized, but no background layer shown

[mtbeek32]

A background layer is configured for WebMercator coordinates, this works fine for vector data.

For grid data, the projection is recognized (could also be combined with vector data), but no background layer is visible

steps to reproduce:

repository: geoDMS project: tst/wmts/cfg/wm.dms request item: /SourceData/read/GridData in map view.

[eoudejans]

The current behavior is that the background layer is searched in context of the unit describing the coordinates.

• For item /SourceData/read/GridData this is unit /SourceData/read.
• For vector geometries this is usually the values unit, ie:

parameter<geometries/WebMercator> test_point := point_xy(665307.894194, 6927029.251316, geometries/WebMercator);

That being said, the DialogData property of Geometries/WebMercator describing the background layer is given as: DialogData = "tms_layer_osm_webmercator". This treeitem can be found in context of geometries. However it cannot be found in context of SourceData/read.

Changing the definition of geometries/webmercator to at least makes the background layer findable:

unit<dpoint> WebMercator : SpatialReference = "EPSG:3857",   DialogData = "Geometries/tms_layer_osm_webmercator";

Resulting in a proper background layer:

[eoudejans]

See line 150 of GraphDataView.cpp and function GetNextDialogDataRef itself:

const TreeItem* topographicItem = GetNextDialogDataRef(geoCrdUnitContext, i, e);

Possible improvements:

• Issue a warning in case the backgroundreference has a value but cannot be found in context of the geocrdunit ie: SourceData/read
• Expand the search scope such that the background reference can be found (can be computationally expensive)
• Add GUI default background layers for several often used projections such as EPSG:4326, EPSG:28992, etc.

@MaartenHilferink any ideas?