Mon, May 27 2002
13:08:44
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Request created by david.a.hastings@noaa.gov (as #1065)
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Mon, 27 May 2002 13:08:41 +0200
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David A Hastings <david.a.hastings@noaa.gov>
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Markus Neteler <neteler@itc.it>
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GRASS and IDRISI
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Mon, 27 May 2002 13:08:41 +0200
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> On Wed, Mar 27, 2002 at 05:49:34PM -0700, David A Hastings wrote:
> > I hope to set up the database so that source (e.g. PERMANENT) data will
> > be readable on both GRASS and Idrisi. GRASS and Idrisi 8-bit
> > uncompressed cell files are identical, one can use links to headers, so
> > that source data are interoperable on both systems. I have been doing
> > this since 1995. If GRASS let one specify an actual 2-byte integer, and
> > specify the byte ordering (say as enhancements to CELLHD files), as is
> > possible in programs such as Photoshop, the interoperability would be
> > better. And Idrisi has had floating point cell files since its
> > inception - though I won't know about compatibility issues with GRASS 5
> > for another few weeks. Finally, if GRASS could let the user force files
> > to remain uncompressed (again, a field in the CELLHD file),
> > interoperability would be helped at the cost of (now cheap) disk space.
>
> If you don't mind, I'll send above to the developers list. Maybe we can do
> something.
I'd love to see you make a suggestion. I would do it myself, but I'm
overwhelmed with the move right now. It has been a BIG pain to me that the
history of the Open GRASS Foundation (which became the Open GIS Consortium
when CERL stopped funding OGF for doing things that were inappropriate in
CERL's eyes) causes the Open GIS Consortium to ignore the best starting
platform for open GIS (e.g. GRASS). Nevertheless, GRASS and Idrisi have
existing "de-facto" interoperability at the file level, and are a great
conceptual model for enhancing such interoperability if they could cooperate
on "just a couple of small detials." The complementarity of GRASS and Idrisi
(and perhaps ERDAS, but this might be less likely), and the research aspect
of both GRASS and Idrisi, should be a great motivation to modestly pursue
such interoperability.
> > Regards to all,
> > David Hastings
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Mon, May 27 2002
13:13:44
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Area changed to wish by mneteler (as #1065)
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Mon, May 27 2002
22:05:08
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Mail sent by egm2@jps.net (as #1065)
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Mon, 27 May 2002 12:59:02 -0700
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"Eric G. Miller" <egm2@jps.net>
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Request Tracker <grass-bugs@intevation.de>
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grass5@grass.itc.it
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Subject |
Re: [GRASS5] [bug #1065] (grass) GRASS and IDRISI
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<20020527195902.GA8497@calico.local>
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On Mon, May 27, 2002 at 01:08:44PM +0200, Request Tracker wrote:
> this bug's URL: http://intevation.de/rt/webrt?serial_num=1065
> -------------------------------------------------------------------------
>
> > On Wed, Mar 27, 2002 at 05:49:34PM -0700, David A Hastings wrote:
> > > I hope to set up the database so that source (e.g. PERMANENT) data will
> > > be readable on both GRASS and Idrisi. GRASS and Idrisi 8-bit
> > > uncompressed cell files are identical, one can use links to headers, so
> > > that source data are interoperable on both systems. I have been doing
> > > this since 1995. If GRASS let one specify an actual 2-byte integer, and
> > > specify the byte ordering (say as enhancements to CELLHD files), as is
> > > possible in programs such as Photoshop, the interoperability would be
> > > better. And Idrisi has had floating point cell files since its
> > > inception - though I won't know about compatibility issues with GRASS 5
> > > for another few weeks. Finally, if GRASS could let the user force files
I suspect GRASS and Idrisi FP formats are significantly different. For
FP rasters, GRASS actually stores the data in a different file and has
an additional header file. Whether float, or double size, each file has
an index of row offsets (int) followed by the data. The data itself is XDR
encoded, and each row may be compressed via zlib. The first byte of
each row flags whether the row data is compressed ('0' - no, '1' - yes).
GRASS5 also has a NULL data file to differentiate 0 from NULL. This is
used with all raster types.
--
Eric G. Miller <egm2@jps.net>
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Thu, May 30 2002
16:48:28
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Request created by hastingsd@un.org
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Re: GRASS and Idrisi file compatibilities
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grass-bugs@intevation.de
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Lotus Notes Release 5.0.3 (Intl) 21 March 2000
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"David A Hastings" <hastingsd@un.org>
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Thu, 30 May 2002 16:51:40 +0700
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Hello Eric,
Many thanks for your comments, recently sent to david.a.hastings@noaa.gov.
I currently find that I can't compose replies in that email system from
here (UN-ESCAP,Bangkok, where I currently work), so am replying from here.
Since I created a dual-boot Linux-Windows system in 1995, I was able to
work with the same uncompressed 8-bit cell files in Idrisi and GRASS, thus
de-facto file-level interoperability. Of course, the headers were
different, but these could be kept in separate directories, so no problem
there.
(If you're familiar with the origins of the Open GIS consortium, and its
avoidance of GRASS, the existing interoperability of GRASS with another GIS
is somewhat interesting. Because of that history, it would be great to see
de-facto GIS interoperability demonstrable more strongly from GRASS, if
that were not much work.)
It would have been nice not to be forced to have automatic compression of
GRASS cell files when they were created. However, this is only a minor
inconvenience to uncompress a cell file to make it compatible with Idrisi's
uncompressed format. (Idrisi also has run-length encoded file compression,
but this used to be error-prone, so I don't know anyone that compresses his
Idrisi files.)
The next hurdle would be integers. To me, the GRASS integer file format is
1980s concepts of portability run wild. Or, perhaps, not updated with the
times. Many current programs handle either byte ordering for integers. If
this were allowed in GRASS, both PC and UNIX byte ordering could be handled
by the software, rather than the (easy, but very bothersome) playing with
dd....conv=swab. Also, as so much integer data is merely 2-byte integers,
a simple 16-bit integer format in GRASS would have been helpful - again
allowing for either byte ordering. (I'd also let the 16 bits be signed or
unsigned with another header flag...)
If GRASS had a 2-byte integer format that could handle either byte ordering
plus signed or unsigned integers, its file-level portability would markedly
increase.
For larger integers, GRASS might keep its current format, which is a
non-standard enhancement useful when numbers get too large for 16 bits.
Perhaps the optional header lines for integers could be something like:
intsigned
intunsigned
motsigned
motunsigned
with int and mot used instead of pc (or intel) and unix (or motorola) to
avoid trademark issues, as well as to avoid the confusion of the various
unix platforms (e.g. alpha)..
Perhaps such terms (or an equivalent) can go into the "format" field
instead of the adjusted "number of bytes per pixel - 1" normally used.
Floating point data might not be worth worrying about yet. Idrisi actually
started with 6-byte floats, based on Turbo Pascal (I believe that was their
original design platform). Later they went with 4 and 8 byte floats.
I hope this isn't too "windy." But I think it better to lay out my ideas
for you to eliminate, than for me to be too brief and have you guessing the
details.
With best regards,
David Hastings
Geographic Information Systems
Space Technology Applications
UN Economic and Social Commission for Asia and the Pacific
UN Building
Rajademnern Nok Avenue
Bangkok 10200, THAILAND
email: hastingsd@un.org
tel: +66-2-288-1457
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Fri, Aug 23 2002
15:38:45
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Area changed to wish by bernhard
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Thu, Nov 4 2004
15:51:36
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Mail sent by guest (as #1065)
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chicken's guts spill our when i rear end them |
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Tue, Mar 7 2006
08:31:17
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Mail sent by msieczka
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David,
What do your comments given in this report look in the light of current Grass
6.1 state? I would be very gratefull if you could post an update here. If you
are not using Grass anymore or are not interested anymore please also drop a
line.
Best,
Maciek
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Tue, Mar 7 2006
14:25:26
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Mail sent by hastingsd@un.org
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Re: [bug #1069] (grass) Re: GRASS and Idrisi file compatibilities
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Maciek Sieczka via RT <grass-bugs@intevation.de>
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David A Hastings <hastingsd@un.org>
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Tue, 7 Mar 2006 20:23:05 +0700
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Dear Maciek,
Many thanks for your message. Actually, I haven't started using GRASS 6
yet, but from what I can see from the raster header format, it's time to do
it. It appears that you have addressed my collected concerns (2-byte
integers, byte ordering, turning off automatic compression). This should
make GRASS defacto interoperable with several other raster systems.
I just upgraded my system with new motherboard and processor, and have a
disk sitting to install. After that I should upgrade my Linux and GRASS.
I think you can close out that wish list (more than a bug...) item.
BTW, I have not had a chance to update my HOWTO on GRASS, and am thinking
that more robust coverage in Wikipedia may be more valuable.
Also BTW, has anyone obtained the source code to Land Analysis System (LAS)
((Google: ADAPS LAS 7.4 ) - currently I have to view the Google cache as
the server seems to be down)? It's USA govt stuff, so has the USG
"non-copyright" (actually a copyright that's not well understood even by
USA civil servants), and could be adapted to turn GRASS into a powerful
image processing system as well as GIS. It might be the best way to go in
that direction, as it involves 23 years of work to date.
With best regards,
David Hastings
Space Technology Applications
UN Economic and Social Commission for Asia and the Pacific
UN Building
Rajademnern Nok Avenue
Bangkok 10200, THAILAND
email: hastingsd@un.org
tel: +66-2-288-1457
fax: +66-2-288-3012
Maciek Sieczka
via RT To: hastingsd@un.org
<grass-bugs@intev cc:
ation.de> Subject: [bug #1069] (grass) Re: GRASS and Idrisi file
compatibilities
07/03/2006 14:31
Please respond to
Maciek Sieczka
via RT
David,
What do your comments given in this report look in the light of current
Grass
6.1 state? I would be very gratefull if you could post an update here. If
you
are not using Grass anymore or are not interested anymore please also drop
a line.
Best,
Maciek
-------------------------------------------- Managed by Request Tracker
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Sat, Jun 17 2006
11:38:50
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Request 1065 merged into 1069 by hbowman (as #1065)
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Sat, Jun 17 2006
11:39:13
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Subject changed to GRASS and Idrisi file compatibilities by hbowman
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