[gdal-dev] Status Report

[Frank Warmerdam]

Folks,

A quick update on what's happening with me, and GDAL.

o I am off the OGDI contract for PCI (and won't be doing any others)
though Stephane is now handling the OGDI contract for PCI, along with
Duncan. 

o I have been retained by Global Geomatics to write a GXF (Geosoft Grid
eXchange Format) driver for OGDI. Gilles has agreed to allow the 
underlying library to be publically distributed as OpenSource six months
after the drivers release within OGDI (so it should be generally available
late next summer). This low level code (gxfopen.c) has been written 
using various CPL services. 

o While arranging for format specs from GeoSoft here in town, Ian Macleod
indicated that Geosoft would be interested in having me write translators
for them. They have an architecture they call DATs (similar to GDB or
GDAL) for accessing raster files. Ian has agreed that where appropriate
I could write translators as low level C libraries which can be distributed
as OpenSource, and higher level DAT code calling the low level library 
which would be proprietary to Geosoft.

My first project with Geosoft is a GeoTIFF DAT, so the low level library
(libtiff, and libgeotiff) already exist. However, I have taken the 
opportunity to add TIFFGetRGBATile() and TIFFGetRGBAStrip() functions 
to libtiff, allowing for more efficient access to files. The existing
API required the application to read the whole file into memory as one
bit array with 32bits (RGBA) per pixel! This code was released to the
libtiff mailing list, and can be seen in:

http://gdal.velocet.ca/rgba_tiff/

This function (TIFFGetRGBAImage()) was used by Global Geomatics geotiff
support, so I hope to get a job upgrading it to use the new methods. 

I am hoping to do a variety of other formats for Geosoft in the future
if this goes well. Geosoft has a very structured development approach,
which includes custom APIs for memory management, file access and lots
of other things. Ian was pleased to hear of the VSI (Virtual System 
Interface) layer which gives an opportunity to hook must standard 
library access for files, and memory. 

o I am still in contact with Spot about writing a DTED validation, and 
header update utility. Unfortunately they aren't willing to let the
source be OpenSource without a steep discount, so my current quote
to them would not lead to any OpenSource results. We will see whether
they decide to proceed. 

o I received the contract from Intergraph for an Imagine to GeoTIFF 
translator, but it specified that all the results would have to be 
signed over to them. Alternatively if I want to retain ownership
of the code they would want a 50% discount. The matter isn't yet 
resolved.

o I have been doing some work on the GDAL core in fits and starts. I
had the raster reading architecture working OK, with drivers for GXF
and GeoTIFF but I have recently torn things apart again to built
in raster tile (block) caches. I want format writers to be able to
concentrate on implementing the IReadBlock(), and IWriteBlock() 
methods with the core taking care of caching to make stuff like the
generic RasterIO() method efficient. 

o I have also been doing a bit of work for Dave Gilbert at Velocet, but
that doesn't really have much to do with GDAL. I am learning PHP (a
server side web scripting language) though!

o I also put Shapelib 1.2 into general release on the GISTrans-L a week
or two ago. This is the version with 3D Shapefile support. After a 
couple more fixes I will likely announce it on comp.infosystems.gis 
and/or ArcView-L. 

o I have done some work to update GeoTIFF web pages last weekend, but I
have yet to get any response from Niles Ritter who hosts the current
out of date pages. It really seems like the GeoTIFF effort has been
hamstrung by principles moving off to other jobs. It suggests to
to me that it is important for the longevity of a project to have a
central web site supported by a group rather than a single individual.

o The GXF format depends on EPSG projection definitions, the same ones
depended on by GeoTIFF, but in a very different format. In following
up on this I found the current information (which is distributed as a
Microsoft Access .mdb file!). It is quite all encompassing, and well
done. At the last OGDI meeting it was suggested that the EPSG (also
known as POSC) projection standards might be adopted within OGDI, and
also that it would likely be adopted by the OpenGIS consortium. 

One project that I would really like to land would be to incorporate 
EPSG support into PROJ.4 (the projections library used by OGDI). I
am hoping the OGDI Research Institute (well, name to be determined)
might be willing to fund my doing work on this. As well as helping 
OGDI this would also be good for GDAL if we adopt PROJ.4 as our base
library, and if the EPSG projection stuff is widely adopted. I can't
really even promote this project though till the OGDI-RI is actually
setup ... hopefully in January. 

I emailed Gerald Evenden (author of PROJ.4) who is now retired. He
says that PROJ.4 isn't really being maintained by anyone and his 
interests have mostly gone on to other things. I had also posted to
comp.infosystems.gis, asking what public domain library people thought
would be a good candidate for a project like mine. I only got two
responses (by email). Not too overwhelming. The one guy was supportive
of PROJ.4, and felt that it would be a good base. 

My dream project is still to get funding to warm up the GeoTIFF standards, 
upgrade to recent EPSG databases, and build a mapping between GeoTIFF and
PROJ.4. I was hoping to promote this to Space Imaging and Spot, but now
I am not so sure that Spot would buy in.

All, in all, my faith that the world is ready for GDAL is faltering a bit. 
Between events at PCI, OpenSource averse clients, and limited response from
the geomatics community I am now kicking around the idea of applying to
work on Linux related projects at Corel. Oiii!

Later,

-----------------------------------+---------------------------------------
Who can give them back their lives | Frank Warmerdam, Programmer for Hire
and all those wasted years? - Rush | http://members.home.com/warmerda
| warmerda at h...
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