[Gdal-dev] floating point bug

Maciek Sieczka werchowyna at pf.pl
Mon May 31 05:04:12 EDT 2004

> Sorry, I don't recall the details.  What that the one that was really a
> BIL file, and GDAL didn't support floating point BIL files?   That
> was resolved by assuming that 32bit files were floating point.  If it
> was really an arc/grid binary grid coverage, could you provide it
> again?

The problem with BIL occured "by the way" when I was trying to
walkover my problem.

The MAIN issue is: FP ArcGrid support in GDAL is faulty IMHO.

below goes our most recent email on this subject
a sample of the problematic file is attached

>> I find it hard to believe that GDAL's AIG driver would misreport a
>> floating point Arc/Info Binary Grid as Int16.  If you can provide a
>> sample Arc/Info grid that demonstrates this problem I will investigate.

> I digged a little more and I'm confused.

> I noticed that whether GDAL recognises the FP ARCGrid as FP or INT
> depends somehow on the proportion and distribution of null/data
> cells in a file but I can't find a simple rule for this (and I may be
> wrong as well). Anyway if the FP grid file is "100% data" it is always
> recognised as FP. But if it contains nulls then GDAL will see it as INT or
> FP dependending on the file itself. Examples for both cases taken out from
> my FP ARCGrid are attached in the arc.tgz. If you need a bigger one please
> let me know. BOTH shold be FLOATING POINT while only ONE is recognised
> properly.

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