[GRASSLIST:1911] Re: i.ortho.photo on osx

Glynn Clements glynn.clements at virgin.net
Sat Nov 29 05:10:10 EST 2003

Richard Greenwood wrote:

> I revisited my problematic project, converted to DCELL and it worked very 
> nicely. Thanks Markus! But, I am confused on FCELL versus DCELL. I assumed 
> that my metric DEM was integers and that converting to feet created a 
> floating point, or double precision DEM, thus avoiding the problem you 
> describe above. But what is the difference between FCELL and DCELL?

FCELL is single-precision floating-point (32 bits, aka C's "float"
type), while DCELL is double-precision (64 bits, C's "double" type).

DCELL is often used as a "generic" type, because it can exactly
represent any value which CELL and FCELL can represent. OTOH
converting from CELL to FCELL can result in loss of accuracy for
integers outside the range ±2^24.

Glynn Clements <glynn.clements at virgin.net>

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