[Xastir] DRG's not cropping white space

[Nick]

Just to catch everyone up:

As per instruction I checked:

You can check yourself: look to see if proj.4 and libgeotiff are in 
/usr/local/lib or /usr/lib.  If /usr/local/lib, they were built from source,
not the repository.

I found that proj.4 was not in either directory.

Finding this, I shifted gears last night and focused on getting my GPS 
and TNC working on the interface.  Took me a little bit to realize I 
need to to use /dev/ttyUSB0 and /dev/ttyUSB1 for the Serial TNC and 
Serial GPS Interface.  Those are working well.

Later tonight I am going to focus on getting the map issue working after 
I get back from getting some green trails maps for around Cle Elum at 
REI in Lynnwood.

Does it matter that the terraserver-topo.geo doesn't seem to have a 
cropping problem?

Cheers and '73

Nick

Tom Russo wrote:
> On Fri, Oct 09, 2009 at 09:43:41AM -0700, we recorded a bogon-computron collision of the <archer at eskimo.com> flavor, containing:
>   
>> On Fri, 9 Oct 2009, Kevin Ratcliff wrote:
>>
>>     
>>> On Fri, Oct 9, 2009 at 12:08 PM, Tom Russo <russo at bogodyn.org> wrote:
>>>       
>>>> Hmmm. ?Well, then, recompiling proj.4 with correct datum shift grids would
>>>> be required regardless, then.
>>>>         
>>> I've been meaning to modify the Ubuntu 9.04 wiki instructions to
>>> address this, but haven't done so yet. I'll try to do it this weekend.
>>>       
>> Nick was hoping to use these maps off-road this weekend.  Guess he's
>> out of luck unless he finds that other package Tom mentioned that
>> has it fixed.
>>     
>
> *IF* the clipping is due to libgeotiff not being compiled against proj.4,
> and the problem that Nick is having is related to proj.4 not being 
> compiled correctly.  That has not been determined, it's just one possibility.
> You brought it up, because that would be one explanation.
>
> Lee almost certainly followed the wiki instructions for building Xastir
> in the VM.  That would mean that libgeotiff was compiled after proj.4 was
> installed from the repositories, meaning that border clipping should still
> work.
>
> We do NOT use proj.4 to do datum shifting in map_tif.c.  The only use of
> proj.4 in map_tif.c is to convert coordinates in the geotiff file from their
> native coordinate system (generally UTM) into lat/lon using GTIFProj4ToLatLong
> --- no datum shift is applied in this step, and the lat/lon produced is
> in the same datum as the original projected coordinate system.  Datum shifting 
> is applied by the code you wrote in datum.c instead.  Since NAD27/NAD83 
> conversion is not an analytic transformation (it requires an interpolation 
> grid to be done correctly) this is at best an approximate shift that would 
> actually be more correctly done by proj.4 (if it is compiled properly with
> the interpolation grids), but that's another matter.  The point is, 
> even if proj.4 is compiled incorrectly, it has no impact on Xastir because 
> Xastir doesn't use proj.4 for exactly the thing that is wrong in the Ubuntu 
> compilation of proj.4.
>
> Even if it did, the error would show up as a few dozen pixels of incorrectly
> cropped or uncropped white border around the map.  Most of the rest of the
> border would be cropped.
>
> Nick implied that no border was being trimmed, which would suggest something
> much more serious, such as Xastir not finding the FGD files or being 
> unable to read them.
>
> I think it is much more likely that there is a problem with reading or
> processing the FGD file than that the issue is related to libgeotiff and
> proj.4.  Nick should try running with debug level set to 16 and see if
> Xastir reports the various things that are printed out by the cropping
> code (such as "Upper left <XXXXXX> <YYYYY>," "Lower Right <xxxxxx> <yyyyyy>,"
> "Tiepoints:," "Datum:", "***** Attempting Datum Conversions",
> "NW neat-line corner =" and so on and so forth, or errors such as 
> "Failed GTIFProj4ToLatLong() call")
>
> And now that I look, if the issue were libgeotiff not being compiled with
> PROJ.4, there would also be error messages such as:
>
>   draw_geotiff_image_map: Problem converting from lat/lon\n
>   Did you follow the instructions for installing PROJ?\n
>
> Nick should definitely try running Xastir from the command line and tell
> us if he sees error messages such as these.  Read permissions of FGD files
> would also be a good thing to check.  Also, if the files are called ".FGD"
> instead of ".fgd", the function "read_fgd_file" will not find it.
>
>