maproom / QMapShack / wiki / DocBasicsMapDem — Bitbucket

The default basic projection used by QMapShack is Mercator. The geographic datum is WGS84. However you can use maps with different projections and datums as QMapShack will re-project them on-the-fly. The same applies to the scale. QMapShack uses a fixed logarithmic scale. All maps will be re-scaled to this scale on-the-fly. All raster maps handled by GDAL have to be wrapped by a virtual map. You can do this with gdalbuildvrt. A virtual map can contain one or several map files (you can replace *.tif with any other extension supported by GDAL, e.g. *.hgt). You can define a no data value, too. This is quite useful for DEM data that does not cover a complete rectangular area: If the files are large it will take a lot of memory and time to display them in the outer zoom levels. You might consider to use gdaladdo to add overview levels to the files. This will create a file My_Map_Name.vrt.ovr next to My_Map_Name.vrt containing scaled overviews by factor 2 4 8 16. A Web Map Tile Service (WMTS) is a standard protocol for serving pre-rendered georeferenced map tiles over the Internet (says Wikipedia). The capabilities of a WMTS server are defines in a XML document named WMTSCapabilities.xml. It can be found on the server: For example there is a variety of free world wide WMTS map from Arcgis. The capability sheet of the topo map can be found at: To use the map you download the XML file and rename it, let's say: World_Topo.wmts. Move the file into QMapShack's map path and you can use the map online. For some servers, the 'capabilities' XML sheet may need some hand tuning (comparing with the above working ones from Arcgis may greatly help in fixing it). For example, there is some detailed info about French IGN WMTS server in the 'maps tips & tricks' section. To access TMS servers you have to define a few properties via XML file. This is an example for definition file with two layers. <,RawHeader>, An optional list of name/value pairs to be inserted into the HTTP header of the request. Some servers want to see special value here. <,MinZoomLevel>, Can be 0..17. 0 is the most detailed level. Below this level tiles from the specified level will be taken and scaled. <,MaxZoomLevel>, Can be 1..18. 1 is the most detailed level. Above this level the map will not be drawn. MinZoomLevel and MaxZoomLevel will be taken as default for the layers. Note: zoom level = 18 - map level <,ServerUrl>, This is the servers URL with placeholders. %1 is for the map level (z), %2 for the column (x) and %3 for the row (y). If the URL contains special characters you have to escape them according to the HTML specification, e.g. & becomes <,MinZoomLevel>, Override the default MinZoomLevel for this layer. Can be 0..17. 0 is the most detailed level. Below this level tiles from the specified level will be taken and scaled. <,MaxZoomLevel>, Override the default MaxZoomLevel for this layer. Can be 1..18. 1 is the most detailed level. Above this level the map will not be drawn. Next to the normal TMS naming scheme for URLs the URL can be formed by a bit of JavaScript. Here is an example for Microsoft's Bing: Source.


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Last Modified: April 22, 2016 @ 1:09 pm