WARNING: Shapefile and image are not the same projection

[Josh Jones]

Hi Pete, Dan and everyone else,

I'm trying to calculate some zonal stats for a stack of KEA images within a shapefile. Despite warping and projection them to the same projection I always get the same error message as GDAL seems to write the projection info in a very slightly different way for the same projection (OSGB36). I've tried manually editing the .proj file of the shapefile but the changes never stick and there is always at least one slight difference.

Is there a fix for this in GDAL ORG or RSGISLib?

Thanks,

Josh

# make sure the layer are in exactly the same projection
print('Reprojecting shapefile')
call (["ogr2ogr", "-t_srs", "EPSG:27700", "./data/GB_CCM21_elementary_OSGB36_proj.shp",  "./data/GB_CCM21_elementary_OSGB36.shp"])

call (["gdalwarp", "-t_srs", "EPSG:27700", "./data/GB_covariables_stack.kea", "./data/GB_covariables_stack_proj.kea"])

# extract zonal stats for elementary catchments
imagestack = './data/GB_covariables_stack_proj.kea'
inputvector = './data/GB_CCM21_elementary_OSGB36_proj.shp'
outputtxt = './output/GB_CCM21_elementary_covars.txt'
zonalattributes = zonalstats.ZonalAttributes(minThreshold=0, maxThreshold=10000, calcCount=False, calcMin=True, calcMax=True, calcMean=True, calcStdDev=True, calcMode=False, calcSum=False)
rsgislib.zonalstats.pixelStats2TXT(imagestack, inputvector, outputtxt, zonalattributes, True, False, zonalstats.METHOD_POLYCONTAINSPIXELCENTER, True)

WARNING: Shapefile and image are not the same projection!
    Image is: PROJCS["OSGB 1936 / British National Grid",GEOGCS["OSGB 1936",DATUM["OSGB_1936",SPHEROID["Airy_1830",6377563.396,299.3249646,AUTHORITY["EPSG","7001"]],AUTHORITY["EPSG","6277"]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",49],PARAMETER["central_meridian",-2],PARAMETER["scale_factor",0.9996012717],PARAMETER["false_easting",400000],PARAMETER["false_northing",-100000],UNIT["metre",1,AUTHORITY["EPSG","9001"]]]
    Shapefile is: PROJCS["OSGB 1936 / British National Grid",GEOGCS["OSGB 1936",DATUM["OSGB_1936",SPHEROID["Airy_1830",6377563.396,299.3249646,AUTHORITY["EPSG","7001"]],AUTHORITY["EPSG","6277"]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433],AUTHORITY["EPSG","4277"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",49],PARAMETER["central_meridian",-2],PARAMETER["scale_factor",0.9996012717],PARAMETER["false_easting",400000],PARAMETER["false_northing",-100000],UNIT["metre",1,AUTHORITY["EPSG","9001"]]]
...Continuing anyway
Started, 25762 features to process.
0% Done
Segmentation fault (core dumped)

[Pete Bunting [pfb]]

Hi Josh,

I don’t know the cause of the error but it isn’t because of the warning about projections.

Probably check that all your polygons are valid - there is a tool in QGIS and you can also check things using: rsgislib.vectorutils.printpolygeom

Otherwise, I’d probably need to look at an example dataset which exhibits the issue.

Cheers Pete

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From: rsgislib...@googlegroups.com <rsgislib...@googlegroups.com> on behalf of Josh Jones <joshua.a...@gmail.com>
Sent: Monday, April 16, 2018 9:00:00 PM
To: RSGISLib Support
Subject: [rsgislib-support] WARNING: Shapefile and image are not the same projection

 

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[Josh Jones]

Thanks for the speedy response Pete.

Geometry seems to be valid.

Sample data available at the link if you have a minute. The shapefiles are derived from a spatial join between the original catchment .gdb and shapefile of points.

https://drive.google.com/open?id=1NXCV27QREI92V10f00qqSbgX09vzMOEf

Thanks,

Josh

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[Daniel Clewley]

Hi Josh,

I’ve had a quick look and also get the same error. It is quite a complicated shapefile with lots of polygons so would recommend checking this as Pete suggested. I’ll try and have a more detailed look later.

As for the projection error there is an argument so it doesn’t print projection warnings (noProjWarning) you are setting this to False, if you set it to True you won’t get the warning about projection.

Thanks,

Dan

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[Josh Jones]

Hi Dan,

QGIS geometry validity tool didn't return any errors. I've since used subsetImgs2CommonExtent to make sure the stack was correct. But still getting

...Continuing anyway
Started, 25762 features to process.
0% Done
Segmentation fault (core dumped)

New image stack here as some of the images in the stack weren't landing in the right place before https://drive.google.com/open?id=1WCSB_P04VslVGgtQyjkbClm1wAeq00BZ

Thanks for having a look,

Josh