Using ST_AsRaster function got a abnormal result

[tlgeo george]

Hello folks,

When I use ST_AsRaster in Postgis, I can't get the expected result.

My SQL: SELECT ST_AsPNG(ST_AsRaster(ST_GeomFromText('POLYGON((4 3,4 2,1 2,1
3,4 3))'),150, 150,ARRAY['8BUI'],ARRAY[4],ARRAY[0])) ;

I write the select result into byte[] and write into disk tiff file in Java.

But I got a file like this:

[image: image.png]

This result file is in the attached file.

I think the right result should contain nodata district ,but my result file
did't.

Any clues will appreciate,thank you very much.
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