GRASS and MapServer: Difference between revisions
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==Raster Maps== | ==Raster Maps== | ||
A | A short example of a layer definition to access a GRASS raster: | ||
<pre> | <pre> | ||
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Notes: | Notes: | ||
* The rasters are limited to values | * The rasters are limited to values from 0 to 255, the values over this are interpreted as 255. Rescale (<code>r.rescale</code>) your maps when necessary. | ||
* You really need to have a CLASS in your layer, otherwise no data will be shown. An empty class is quite fine to show the whole map. | * You really need to have a CLASS in your layer, otherwise no data will be shown. An empty class is quite fine to show the whole map. | ||
See the [[Color tables]] wiki page for more on exporting raster color tables as SLD XML rules using the {{AddonCmd|r.colors.out_sld}} addon script. | |||
==Vector Maps== | ==Vector Maps== | ||
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* You need to have GDAL with OGR and GRASS support for this to work. Note, that in this [http://grass.itc.it/start.html example] the maps are first exported to shapefiles. This is no longer necessary, as the maps can be accessed directly with OGR. | * You need to have GDAL with OGR and GRASS support for this to work. Note, that in this [http://grass.itc.it/start.html example] the maps are first exported to shapefiles. This is no longer necessary, as the maps can be accessed directly with OGR. | ||
* Usually GRASS layers have no names and the layer number is used in DATA. However, it is possible that they do have names. This can happen for example when importing files with v.in.dxf, as the module keeps the dxf-file layer names and stores them into the GRASS vector. The layer names, if such there are, can be found in <tt>/path/to/grassdb/mapset/location/vector/vectorname/dbln</tt>, or with <code>ogrinfo -ro /path/to/grassdb/mapset/location/vector/vectorname/dbln</code>. Why this is so important is because if there are layer names defined, these layers cannot be accessed through the layer number with OGR. They ''have'' to be accessed through the layer name. | * Usually GRASS layers have no names and the layer number is used in DATA. However, it is possible that they do have names. This can happen for example when importing files with v.in.dxf, as the module keeps the dxf-file layer names and stores them into the GRASS vector. The layer names, if such there are, can be found in <tt>/path/to/grassdb/mapset/location/vector/vectorname/dbln</tt>, or with <code>ogrinfo -ro /path/to/grassdb/mapset/location/vector/vectorname/dbln</code>. Why this is so important is because if there are layer names defined, these layers cannot be accessed through the layer number with OGR. They ''have'' to be accessed through the layer name. | ||
==Examples and useful links== | ==Examples and useful links== | ||
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* [http://grass.itc.it/start.html Example] of GRASS with MapServer. | * [http://grass.itc.it/start.html Example] of GRASS with MapServer. | ||
* [http://mapserver.gis.umn.edu UMN Mapserver homepage] | * [http://mapserver.gis.umn.edu UMN Mapserver homepage] | ||
* [http://idea.isnew.info/how-to-set-up-mapserver-with-grass-gis-support.html How to set up MapServer with GRASS GIS support] | |||
[[Category:Documentation]] | |||
[[Category:Web Servers]] | |||
Latest revision as of 20:42, 15 August 2016
GRASS maps from mapfiles
MapServer needs a mapfile containing the information, how to create the maps. Examples of these can be found, so here you'll find GRASS specific information.
Raster Maps
A short example of a layer definition to access a GRASS raster:
LAYER NAME "Example" TYPE RASTER STATUS ON DATA "/path/to/grassdb/location/mapset/cellhd/example" CLASS NAME "Example" # You need to have a class definition in the layer END END
Notes:
- The rasters are limited to values from 0 to 255, the values over this are interpreted as 255. Rescale (
r.rescale) your maps when necessary. - You really need to have a CLASS in your layer, otherwise no data will be shown. An empty class is quite fine to show the whole map.
See the Color tables wiki page for more on exporting raster color tables as SLD XML rules using the r.colors.out_sld addon script.
Vector Maps
A short example of a layer definition to access a GRASS vector:
LAYER
NAME "Example"
TYPE LINE
STATUS ON
CONNECTIONTYPE OGR
CONNECTION "/path/to/grassdb/mapset/location/vector/example/head"
DATA "1" # Layer number
CLASS # You need to have a class definition; otherwise nothing is shown on the map
NAME "Example"
COLOR 155 155 0
END
END
Notes:
- You need to have GDAL with OGR and GRASS support for this to work. Note, that in this example the maps are first exported to shapefiles. This is no longer necessary, as the maps can be accessed directly with OGR.
- Usually GRASS layers have no names and the layer number is used in DATA. However, it is possible that they do have names. This can happen for example when importing files with v.in.dxf, as the module keeps the dxf-file layer names and stores them into the GRASS vector. The layer names, if such there are, can be found in /path/to/grassdb/mapset/location/vector/vectorname/dbln, or with
ogrinfo -ro /path/to/grassdb/mapset/location/vector/vectorname/dbln. Why this is so important is because if there are layer names defined, these layers cannot be accessed through the layer number with OGR. They have to be accessed through the layer name.
Examples and useful links
- Example of GRASS with MapServer.
- UMN Mapserver homepage
- How to set up MapServer with GRASS GIS support