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Hi.

I've just tried to create a large PNG raster mosaic. I get this error in the log file:

PNGRASTER writer: libpng: Image width exceeds user limit in IHDR
PNGRASTER writer: libpng: Image height exceeds user limit in IHDR
PNGRASTER writer: libpng: Invalid IHDR data
PNGRASTER writer: Failed to write dataset ....

The tile grid is 6 tiles wide and 12 tiles high, and each tile is 20000x20000 pixels.

But what is the effective limit of a PNGRASTER output ?

According to the libpng documentation, PNG allows 2^31-1 rows and columns, but libpng has "arbitrarily" set the maximum to 1 million. And that's well below my max 240K requirement.

Cheers

What do you mean by "max 240K requirement"? Your tile is 400 megapixels, which is fairly large.

My recommendation would be to try progressively smaller tile sizes until you get it working.

I was unable to find any hard limitations in the FME docs.

I too read the maximum width as 1 million. Given that you should have 120,000 x 240,000 then it is confusing. Can you log or inspect the data before it goes to the writer? Just to confirm what the exact characteristics of that raster are (num cols, num rows, cell size, etc).

With that info I can check with our developers to see if they know what the problem might be. In fact I can check anyway to see why 1,000,000 is the maximum.

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