Timeline for Mapserver / QGis and DEM GeoTIFF different nodata values behaviour
Current License: CC BY-SA 4.0
13 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jun 12, 2018 at 18:27 | vote | accept | Ronan L. | ||
| Jun 5, 2018 at 11:16 | answer | added | Ronan L. | timeline score: 2 | |
| Jun 5, 2018 at 9:23 | comment | added | Vince | Welcome to GIS SE. As a new user, please take the Tour, which explains how our "Focused question / Best answer" model operates. Please Edit the question in response to requests for clarification. It's not fair to those who would answer to need to mine the comments for critical information. | |
| Jun 5, 2018 at 9:10 | comment | added | user30184 | If MapServer is using -32768 as nodata and writes that also correctly into the GeoTIFF metadata then it is technically right but I do not know if QGIS interprets the metadata. I am not sure is alpha works with float32 1 band tiff but have a try with gdal_translate. | |
| Jun 5, 2018 at 8:49 | comment | added | Ronan L. |
also adding "wcs_rangeset_nullvalue" "-99999"in my WCS metadata makes another strange behaviour… No data values became 0 ! But alpha channel might be a solution but is it possible with 1 band float32 tiff?
|
|
| Jun 5, 2018 at 8:31 | comment | added | user30184 | Ok, you have GDAL outputformat already but GDAL driver does not have direct creation option for nodata gdal.org/frmt_gtiff.html. How about adding alpha? | |
| Jun 5, 2018 at 8:19 | comment | added | user30184 | If you want to know what really happens read your WCS service with direct GetCoverage requests with curl, save the result on disk and check with gdalinfo. But I believe that your issue is real. Perhaps you must write your own GDAL outputformat for image/tiff mapserver.org/mapfile/outputformat.html | |
| Jun 5, 2018 at 8:15 | comment | added | Ronan L. | Yes, because in fact I need to share my DEM on a mapserver. It seems that my tif file appears correct when directly opened in QGIS3 but not while served via MasServer 7. | |
| Jun 5, 2018 at 8:09 | comment | added | user30184 | And do you read the image into QGIS through WCS? | |
| Jun 5, 2018 at 7:52 | comment | added | Ronan L. | Thanks for your comment: by -32768 I mean: When I select my merged tif file and I click with the "info" icon on a zone where I know there is no data I get a "Sans données" in my result window I translated as "No data" When I do the same thing on my layer from my mapserver map I get -32768, when I click in a zone with values I get a correct value. And yes I defined a WCS coverage corresponding to the maximum extent (rectangle) of my DEM datas | |
| Jun 5, 2018 at 7:37 | comment | added | user30184 | What do you mean with "this layer has now -32768 value where a "nodata" must be found"? You seem to have configurered the tif as a WCS coverage, do you mean that the output of WCS GetCoverage in image/tiff format has that other nodata value? | |
| Jun 5, 2018 at 7:31 | review | First posts | |||
| Jun 5, 2018 at 7:47 | |||||
| Jun 5, 2018 at 7:29 | history | asked | Ronan L. | CC BY-SA 4.0 |