Some GDAL feedback

[Frank Warmerdam]

Ben Discoe wrote:
> 
> Hi Frank,
> 
> I spent some time this evening on beginning to port the VTP code onto GDAL,
> starting with the support for elevation rasters. (I'm using the
> headers/binaries version you released for Win32.) Some small points of
> feedback.
> 
> On the documentation page "GDAL API Tutorial",
> 
> 1. It would be nice to mention the name of the main header to include. As
> far as i could determine, this is "gdal.h" for C programs, and "gdal_priv.h"
> for C++.

Ben,

I have added them into the first (opening) example. 

> 2. The C example code for opening a dataset doesn't look right; "hDataset =
> ...; if (poDataset == ...)"

Fixed.

> 3. Under 'Getting Dataset Information', the C++ example doesn't look right;
> i suspect that `s' should be `%s', d should be %d etc. in a few format
> strings.

This was a problem with the way Doxygen was processing the code. I have put
all the code into \code segments, and things look proper now. 

> Overall, i found the tutorial to be excellent and i was able to get rapidly
> to the point of using GDAL to read SDTS DEMs, with a very small amount of
> code; it's a wonderful improvement over my previous body of code which
> called some antique version of LibSDTS, with great complexity.
> 
> One unresolved question: i believe the method GDALRasterBand::GetUnitType()
> should indicate whether the vertical units are 'feet' or 'meters', and i
> know that this information is contained in the SDTS DEMs that i am reading.
> However, GetUnitType() is only returning an empty string, on either type of
> file.

Of course, what methods are actually implemented are format dependent, and I
don't think GetUnitType() had actually been implemented for any formats yet!
I have added this to the SDTS driver, added a C cover for GetUnitType() and
add code to gdalinfo to report the units type if not empty. The SDTS 
driver will now return "m" or "ft". 

This is in CVS, and will appear in the next release. You might want to work
from CVS. 

> One of the big complaints i've had from people trying to build the VTP code,
> especially on Linux, is the very large number of dependent libraries, each
> of which have to be downloaded, installed/configured and built. I look
> forward to leveraging GDAL/OGR to greatly reduce the number of dependencies!

Well, now you have added another (GDAL), but built with most subcomponents 
"built in" GDAL need not have many depenencies. 

I appreciate your constructive feedback.

Best regards,

---------------------------------------+--------------------------------------
I set the clouds in motion - turn up | Frank Warmerdam, warmerdam at p...
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush | Geospatial Programmer for Rent