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How do you classify raster data in MapServer?
Classifying raster data in MapServer is accomplished by pre-classifying all expected input values and using that table of classification results to lookup each pixel as it is rendered.
Do you need a DATA statement in MapServer?
No DATA statement is required because MapServer will fetch the filename of the raster files from the Location attribute column in the hp2.dbf file for records associated with polygons in hp2.shp that intersect the current display region. The polygons in hp2.shp should be rectangles representing the footprint of the corresponding file.
How are data files interpreted relative to the shapepath?
The DATA file is interpreted relative to the SHAPEPATH, much like shapefiles. Though not shown rasters can have PROJECTION, METADATA , PROCESSING, MINSCALE, and MAXSCALE information. It cannot have labels, CONNECTION, CONNECTIONTYPE, or FEATURE information. Rasters can be classified in a manner similar to vectors, with a few exceptions.
How is MapServer used to make pseudo colored maps?
Traditionally MapServer has been used to produce 8 bit pseudo-colored map displays generated from 8bit greyscale or pseudocolored raster data. However, if the raster file to be rendered is actually 24bit (a red, green and blue band) then additional considerations come into play.
Is there support for non 8bit rasters in MapServer 4.4?
As of MapServer 4.4 support has been added for classifying non-8bit raster inputs. That is input rasters with values outside the range 0-255. Mostly this works transparently but there are a few caveats and options to provide explicit control.
What does one band classification mean in MapServer?
In particular this means that including even a single CLASS declaration in a raster layer will result in the raster layer being rendered using the one band classification rules instead of other rules that might have applied (such as 3 band RGB rendering). As of MapServer 4.4 support has been added for classifying non-8bit raster inputs.
How is MapServer able to resample GDAL rasters?
MapServer is able to resample GDAL rasters on the fly into new projections. Non-GDAL rasters may only be up or down sampled without any rotation or warping. Raster warping kicks in if the projection appears to be different for a raster layer than for the map being generated.
How to make the rendered image transparent in GeoServer?
I have no way of testing if the rendered image works in Geoserver, but here is an example using the L.ImageOverlay directive, where transparency works out of the box: I have had the same problem. After some tests this code works for me:
What does a raster layer Declaration look like?
A simple raster layer declaration looks like this. The DATA file is interpreted relative to the SHAPEPATH, much like shapefiles. Though not shown rasters can have PROJECTION, METADATA , PROCESSING, MINSCALE, and MAXSCALE information. It cannot have labels, CONNECTION, CONNECTIONTYPE, or FEATURE information.