topic Re: Problem with NumPyArrayToRaster in Transportation Questions

Problem with NumPyArrayToRaster

FabianBlau — Sun, 12 Dec 2021 05:06:11 GMT

NumPyArrayToRaster ignores the lower_left_corner if an extent ist set. The result is stupid.
I did following to check the problem:

New mxd.
Create Random Raster with defaults.
Python window:

>>> LL = arcpy.Raster('CreateRandom1').extent.lowerLeft
>>> LL.X += 100
>>> LL.Y += 100
>>> numras = arcpy.RasterToNumPyArray('CreateRandom1', LL, 100, 100, arcpy.Raster('CreateRandom1').noDataValue)
>>> numras.shape
(100, 100)
>>> LL
<Point (100.0, 100.0, #, #)>
>>> outras = arcpy.NumPyArrayToRaster(numras, LL, 1, 1, arcpy.Raster('CreateRandom1').noDataValue)
>>> arcpy.env.extent
>>> arcpy.env.extent = arcpy.Raster('CreateRandom1').extent
>>> outras1 = arcpy.NumPyArrayToRaster(numras, LL, 1, 1, arcpy.Raster('CreateRandom1').noDataValue)

Results:
CreateRandom1 and outras (without extent):
[ATTACH=CONFIG]13488[/ATTACH]
CreateRandom1 and outras1 (with extent, yellow:NoData)
[ATTACH=CONFIG]13489[/ATTACH]

The LL-Parameter is unused in outras1. The extent is not the extent of the NumPyArray. outras2 is set to the upperleft-corner of the extent.
In my opinion this is wrong.
Solution: Setting the extent before calling NumPyArrayToRaster. Maybe it is necessary to buffer the extent for other reasons before changing it.

Re: Problem with NumPyArrayToRaster

PhilMorefield — Mon, 16 Apr 2012 19:02:13 GMT

I don't get the same results as you. When I follow your steps exactly, LL is not unused for outras1. It lines up in exactly the same place as outras. I'm using AGD 10.0, service pack 4.

Also, I'm not sure what you're trying to show by changing the extent. That won't change where the rasters line up. By default, the extent window is set to the maximum of your inputs ('CreateRandom1' in this case). Setting the extent to 'CreateRandom1.extent' doesn't change anything at all, since that is the input with the maximum extent.

Re: Problem with NumPyArrayToRaster

Anonymous User — Sun, 12 Dec 2021 05:06:15 GMT

Original User: fabl

I dont use service pack 4. Maybe the problem is solved there. I will check this.

By default there is no extent set:

>>> print arcpy.env.extent
None

It is possible to set one on the environments Application-level, of course. But I did not so.

Re: Problem with NumPyArrayToRaster

PhilMorefield — Tue, 17 Apr 2012 11:54:21 GMT

By default there is no extent set:

Ah yes, you're right. I must have set this a while ago.