Opened 22 years ago
Closed 20 years ago
#199 closed defect (fixed)
Raster map queries
Reported by: | Owned by: | warmerdam | |
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Priority: | high | Milestone: | |
Component: | MapServer C Library | Version: | 4.1 |
Severity: | normal | Keywords: | |
Cc: | mcilhagga@… |
Description
Hi, a long standing wish is the possibility of raster map queries. We desire the possibility to query pixel values from displayed raster maps. It were great to have that implemented. Daniel, just sitting besides me here at Trento, mentioned that the display function and the raster file opening might need to be separated for this task. The temporal solution to make vector polygons from a raster field representation does not make too much sense.... Kind regards Markus Neteler
Change History (7)
comment:2 by , 21 years ago
Cc: | added |
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Owner: | changed from | to
Status: | assigned → new |
Version: | 3.5 → 4.1 |
Reassigned to Frank as per comment #1. Also setting version to 4.1 since there is no time for this in 4.0
comment:3 by , 21 years ago
Status: | new → assigned |
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comment:4 by , 20 years ago
Frank, we may have some funding opportunities to get this completed. Any idea how much work would be involved in providing raster query support? This would have to be for GDAL sources. We were talking here about some of the issues in dealing with raster querying (ie. do you do the closest pixel to the point click, or take an average). For this particular case, a closest pixel value would be perfectly acceptable. Dave McIlhagga
comment:5 by , 20 years ago
Cc: | added |
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comment:6 by , 20 years ago
The basic capability would be not too hard. However, when Steve and I talked about it we also considered some other possible addition ... basically making mapserver more aware of information about the underlying rasters. I don't remember all the details of that, and can't seem to find the email where we discussed it now. The most obvious thing to implement would be returning the pixel value(s) at the picked location. However thing we also might want to consider: o interpolating values at pick location from 4 nearest pixel for subpixel accuracy. o extracting pixel windows - pull a 3x3 window around pick point for instance. o extracting all pixels in a query box/polygon/etc - what kinds of constraints are supported for shape queries? o do we return scaled or unscaled values? (presumably unscaled by default). o do we have an option to return class name for classified rasters?
comment:7 by , 20 years ago
Resolution: | → fixed |
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Status: | assigned → closed |
Raster queries are now essentially complete in the 4.3 source tree. Code in maprasterquery.c. See details at: http://mapserver.gis.umn.edu/cgi-bin/wiki.pl?RasterQuery
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