[Gdal-dev] gdal/mapserver debug output, What does it mean?

[Stephen Woodbridge]

Hi Frank,

I am looking into tuning GDAL/mapserver for a bunch of raster data and I 
remember you saying that you output additional GDAL info when DEBUG is 
on. What does it mean? and is it helpful in tuning mapserver or 
determining what overviews I need to generate.


[Tue Mar 27 23:31:37 2007] [error] [client 129.44.191.48] [Tue Mar 27 
23:31:37 2007].930822 msDrawRasterLayerLow(test): entering., referer: 
http://localhost/sw/
[Tue Mar 27 23:31:37 2007] [error] [client 129.44.191.48] [Tue Mar 27 
23:31:37 2007].999147 msDrawGDAL(): src=3980,3648,232,185, 
dst=0,0,500,400, referer: http://localhost/sw/
[Tue Mar 27 23:31:37 2007] [error] [client 129.44.191.48] [Tue Mar 27 
23:31:37 2007].999196 msDrawGDAL(): red,green,blue,alpha bands = 
1,2,3,0, referer: http://localhost/sw/
[Tue Mar 27 23:31:38 2007] [error] [client 129.44.191.48] [Tue Mar 27 
23:31:38 2007].122412 msDrawMap(): Layer 0 (test), 0.192s, referer: 
http://localhost/sw/

I assume the interesting part is the src= and dst= is there other output 
that I should be looking at? how would I turn that on?

As I zoom out I get lots of records like the above. I assume one for 
every tif file that gets opened. I currently do not have any overviews 
built into the image files. I am also wondering at what point does it 
make sense to create an external overview and if there are any scripts 
that would generate these.

All the data is in 3.75x3.75 minute squares in geographic projection and 
is a mix of one and two meter per pixel resolution imagery.

Thanks,
   -Steve