A question about the rasterio precision & python floats (Pixel width & height)
|
thomaswanderer@...
Thank you for the info. I saw shorter values tan in QGIS and those came from Python's float limitations. When using the Decimal class I also get the same over-precise values. |
|
|
|
Sean Gillies
Hi, On Mon, May 25, 2020 at 3:30 AM <thomaswanderer@...> wrote:
QGIS and rasterio both use GDAL to read raster data and all of these use double precision floats to store values of the georeferencing matrix. I believe you're seeing different string representations of the same numbers. Since the hex representations of the two numbers are the same, I suspect the values shown by QGIS are overly precise and that the last digits are meaningless. >>> 0.0008333333299974727193.hex() '0x1.b4e81b312a043p-11' >>> 0.0008333333299974727.hex() '0x1.b4e81b312a043p-11' Sean Gillies |
|
|
|
thomaswanderer@...
When opening my raster with QGIS, I can see the Pixel Size of my raster as:
When I read he same raster with rasterio, I get pixel size values with a lower precision and I guess this causes some problems when calculating new affines for another extent
I have tries to pass the decimal_precision=X when opening my raster with rasterio, but this has no effect. I guess this is a general float problem on my system. My suggestion therefore would be to use python Decimals or any other type representing real floats. |
|
|