[Gdal-dev] Help with overviews/pyramids

[Bill Binko]

On Wed, 22 Jun 2005, Frank Warmerdam wrote:

> On 6/22/05, Bill Binko <bill at binko.net> wrote:
> > ERROR 1: TIFFAppendToStrip:overview.tiff: Write error at scanline 704
> > ERROR 1: TIFFAppendToStrip:overview.tiff: Write error at scanline 705
> 
> Bill, 
> 
> Is there any chance that your resulting overview is larger than 4GB
> or that the input ecw file is too large to hold in RAM in uncompressed
> format?    The error looks like an "out of space" or >4GB related
> problem. 

I don't think so... the files are displayed fine in Mapserver with a 
TILEINDEX, even when multiple tiles are displayed.  It gets slow (hence 
this effort) when you zoom out, but there's no failure.

The files range from 1 - 13 MB compressed, and I'm only trying the first 
ten, so the compressed total would be less than 130MB.  Certainly that 
wouldn't uncompress to over 1GB of physical and 1GB of virtual memory?

Overall, I have 855 of these totalling about 6GB (including metadata 
files).

Another reason I doubt that its a memory issue is if I do the same command 
line with -of bmp instead of tiff, I get this:

[bill at fastcat ecw_rgb]$ gdal_merge.py -o overview.bmp -of bmp -ps 10 10 -v `ls -1 dq*.ecw | head -10`

Filename: dq2807ne.ecw
File Size: 6272x7019x3
Pixel Size: 1.000000 x -1.000000
UL:(518476.607000,3041884.156000)   LR:(524748.607000,3034865.156000)
.....

With no errors.  However, overview.bmp is just as useless -- its corrupt 
in any viewer I've tried.

Thanks for the help Frank (et al)

Bill