Errors when running python gdal.grid with basic parameters

Question

There are a few problems when I run the following code.

1. Image comes out flipped vertically, even though lat lon is input correctly
2. I have to run the code twice for it to run properly (so wierrd)
3. I also get the following errors:

 ERROR 4: `result.tif' not recognized as a supported file format.
 ERROR 4: Unable to open result.tif to obtain file list.
 ERROR 1: Deleting result.tif failed:
 Permission denied

I use the following data in the points.csv:

 lat lon value
 39.545 -75.78 0.001034494
 39.555 -75.78 0.001033509
 39.565 -75.78 0.001032392
 39.575 -75.78 0.001001829
 39.585 -75.78 0.00094428
 39.595 -75.78 0.000940016
 39.605 -75.78 0.000897172
 39.615 -75.78 0.000896742
 39.625 -75.78 0.000896021

And here is the code...

# create the csv and vrt file
vrt_file = """<OGRVRTDataSource>
 <OGRVRTLayer name="points">
 <SrcDataSource>points.csv</SrcDataSource>
 <GeometryType>wkbPoint</GeometryType>
 <GeometryField encoding="PointFromColumns" x="lon" y="lat" z="value"/>
 </OGRVRTLayer>
</OGRVRTDataSource>"""
with open("points.vrt", "w") as f:
 f.write(vrt_file.strip())
# perform gridding and RGB rastering
# for some reason this has to run twice????
gdal.AllRegister()
gdal.Grid('result.tif',
 'points.vrt',
 format='GTiff',
 outputType=gdal.GDT_Float32,
 algorithm='linear:radius=0.5',
 zfield='value')
# plot, comes out flipped on accident
im = gdal.Open('result.tif').ReadAsArray()
im = plt.imshow(im)

Answer 1

You can solve this issue by assigning gdal.Grid() to a variable, like output = gdal.Grid() and then immediately assign that variable to 'None', so after you run your model, output = None.

It's apparently a 'gotcha' when using gdal.Grid() in Python. This prevents the error of having to run the model twice and not have that other error where it says that your result is not a TIFF file.