[GRASS-user] More QUESTIONS !?

GRASS GRASS user
1

Hi!

Well... I know that I only have questions (and a lot). Hope
this will change in time...

1. I tried to install wxgrass but I get an error (see
attached screenshot). I followed the steps described in
http://www.les-ejk.cz/english/wxgrass-new-grass-gui-1

2. I can't find a How-To install grassaddons for a
beginner? I got some of the extensions (which end in .tgz)
installed with GEM. But I really have a hard time to
install for example i.pr (I really looked almost
everywhere... :expressionless: )

3. Is there a link (image to image) utility so one can
compare pixel-by-pixel 2 images of the region but with a
different date of acquisition? I try with i.spectral but I
don't know how to load an image to the monitor which is
selected to choose a location. Any ideas?

4. Why is the newbie forum not active? I mean the link in
the grass webpage doesn't work!

5. Once I finish some work related with my studies I would
like to write a practical How-To for absolute beginners.
Are there any kinds of directions?

Thank you in Advance -- Waiting for helpful hints!

                        .
         Nikos Alexandris - Ph.D. Candidate
                        .
            Department of Remote Sensing
                       and
            Landscape Information Systems
                     (FeLIS)
                        .
      Faculty of Forestry and Natural Environment
          Albert-Ludwigs-University Freiburg
                        .
            Tel. +49 (0) 761 203 3697
            Fax. +49 (0) 761 203 3701
             Skype: Nikos.Alexandris
                        .
           Address: Tennenbacher str. 4
              D-79106 Freiburg i. Br.
                     Germany
                        .

2

Nikos Alexandris wrote:

Hi!

Well... I know that I only have questions (and a lot). Hope
this will change in time...

1. I tried to install wxgrass but I get an error (see
attached screenshot). I followed the steps described in
http://www.les-ejk.cz/english/wxgrass-new-grass-gui-1

2. I can't find a How-To install grassaddons for a
beginner? I got some of the extensions (which end in .tgz)
installed with GEM. But I really have a hard time to
install for example i.pr (I really looked almost
everywhere... :expressionless: )

3. Is there a link (image to image) utility so one can
compare pixel-by-pixel 2 images of the region but with a
different date of acquisition? I try with i.spectral but I
don't know how to load an image to the monitor which is
selected to choose a location. Any ideas?

4. Why is the newbie forum not active? I mean the link in
the grass webpage doesn't work!

5. Once I finish some work related with my studies I would
like to write a practical How-To for absolute beginners.
Are there any kinds of directions?

Thank you in Advance -- Waiting for helpful hints!

                        .
         Nikos Alexandris - Ph.D. Candidate
                        .
            Department of Remote Sensing
                       and
            Landscape Information Systems
                     (FeLIS)
                        .
      Faculty of Forestry and Natural Environment
          Albert-Ludwigs-University Freiburg
                        .
            Tel. +49 (0) 761 203 3697
            Fax. +49 (0) 761 203 3701
             Skype: Nikos.Alexandris
                        .
           Address: Tennenbacher str. 4
              D-79106 Freiburg i. Br.
                     Germany
                        .

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3

Hi,

which version of grass are you using?

Martin

$ g.tempfile help

Description:
Creates a temporary file and prints the file name.

Keywords:
general

Usage:
g.tempfile pid=value [--verbose] [--quiet]

Flags:
--v Verbose module output
--q Quiet module output

Parameters:
  pid Process id to use when naming the tempfile

2007/11/1, Nikos Alexandris <nikos.alexandris@felis.uni-freiburg.de>:

Nikos Alexandris wrote:
>
> Hi!
>
> Well... I know that I only have questions (and a lot). Hope
> this will change in time...
>
> 1. I tried to install wxgrass but I get an error (see
> attached screenshot). I followed the steps described in
> http://www.les-ejk.cz/english/wxgrass-new-grass-gui-1
>
> 2. I can't find a How-To install grassaddons for a
> beginner? I got some of the extensions (which end in .tgz)
> installed with GEM. But I really have a hard time to
> install for example i.pr (I really looked almost
> everywhere... :expressionless: )
>
> 3. Is there a link (image to image) utility so one can
> compare pixel-by-pixel 2 images of the region but with a
> different date of acquisition? I try with i.spectral but I
> don't know how to load an image to the monitor which is
> selected to choose a location. Any ideas?
>
> 4. Why is the newbie forum not active? I mean the link in
> the grass webpage doesn't work!
>
> 5. Once I finish some work related with my studies I would
> like to write a practical How-To for absolute beginners.
> Are there any kinds of directions?
>
> Thank you in Advance -- Waiting for helpful hints!
>
>
>
> .
> Nikos Alexandris - Ph.D. Candidate
> .
> Department of Remote Sensing
> and
> Landscape Information Systems
> (FeLIS)
> .
> Faculty of Forestry and Natural Environment
> Albert-Ludwigs-University Freiburg
> .
> Tel. +49 (0) 761 203 3697
> Fax. +49 (0) 761 203 3701
> Skype: Nikos.Alexandris
> .
> Address: Tennenbacher str. 4
> D-79106 Freiburg i. Br.
> Germany
> .
>
> _______________________________________________
> grassuser mailing list
> grassuser@grass.itc.it
> http://grass.itc.it/mailman/listinfo/grassuser
>
>
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Martin Landa <landa.martin@gmail.com> * http://gama.fsv.cvut.cz/~landa *

4

I run GRASS 6.2.2 under Ubuntu 7.10.

I have tried several ways (?) but no success.

Martin Landa-2 wrote:

Hi,

which version of grass are you using?

Martin

$ g.tempfile help

Description:
Creates a temporary file and prints the file name.

Keywords:
general

Usage:
g.tempfile pid=value [--verbose] [--quiet]

Flags:
--v Verbose module output
--q Quiet module output

Parameters:
  pid Process id to use when naming the tempfile

2007/11/1, Nikos Alexandris <nikos.alexandris@felis.uni-freiburg.de>:

Nikos Alexandris wrote:
>
> Hi!
>
> Well... I know that I only have questions (and a lot). Hope
> this will change in time...
>
> 1. I tried to install wxgrass but I get an error (see
> attached screenshot). I followed the steps described in
> http://www.les-ejk.cz/english/wxgrass-new-grass-gui-1
>
> 2. I can't find a How-To install grassaddons for a
> beginner? I got some of the extensions (which end in .tgz)
> installed with GEM. But I really have a hard time to
> install for example i.pr (I really looked almost
> everywhere... :expressionless: )
>
> 3. Is there a link (image to image) utility so one can
> compare pixel-by-pixel 2 images of the region but with a
> different date of acquisition? I try with i.spectral but I
> don't know how to load an image to the monitor which is
> selected to choose a location. Any ideas?
>
> 4. Why is the newbie forum not active? I mean the link in
> the grass webpage doesn't work!
>
> 5. Once I finish some work related with my studies I would
> like to write a practical How-To for absolute beginners.
> Are there any kinds of directions?
>
> Thank you in Advance -- Waiting for helpful hints!
>
>
>
> .
> Nikos Alexandris - Ph.D. Candidate
> .
> Department of Remote Sensing
> and
> Landscape Information Systems
> (FeLIS)
> .
> Faculty of Forestry and Natural Environment
> Albert-Ludwigs-University Freiburg
> .
> Tel. +49 (0) 761 203 3697
> Fax. +49 (0) 761 203 3701
> Skype: Nikos.Alexandris
> .
> Address: Tennenbacher str. 4
> D-79106 Freiburg i. Br.
> Germany
> .
>
> _______________________________________________
> grassuser mailing list
> grassuser@grass.itc.it
> http://grass.itc.it/mailman/listinfo/grassuser
>
>
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--
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5

You need GRASS 6.3.

2007/11/1, Nikos Alexandris <nikos.alexandris@felis.uni-freiburg.de>:

I run GRASS 6.2.2 under Ubuntu 7.10.

I have tried several ways (?) but no success.

Martin Landa-2 wrote:
>
> Hi,
>
> which version of grass are you using?
>
> Martin
>
> $ g.tempfile help
>
> Description:
> Creates a temporary file and prints the file name.
>
> Keywords:
> general
>
> Usage:
> g.tempfile pid=value [--verbose] [--quiet]
>
> Flags:
> --v Verbose module output
> --q Quiet module output
>
> Parameters:
> pid Process id to use when naming the tempfile
>
>
> 2007/11/1, Nikos Alexandris <nikos.alexandris@felis.uni-freiburg.de>:
>>
>>
>>
>> Nikos Alexandris wrote:
>> >
>> > Hi!
>> >
>> > Well... I know that I only have questions (and a lot). Hope
>> > this will change in time...
>> >
>> > 1. I tried to install wxgrass but I get an error (see
>> > attached screenshot). I followed the steps described in
>> > http://www.les-ejk.cz/english/wxgrass-new-grass-gui-1
>> >
>> > 2. I can't find a How-To install grassaddons for a
>> > beginner? I got some of the extensions (which end in .tgz)
>> > installed with GEM. But I really have a hard time to
>> > install for example i.pr (I really looked almost
>> > everywhere... :expressionless: )
>> >
>> > 3. Is there a link (image to image) utility so one can
>> > compare pixel-by-pixel 2 images of the region but with a
>> > different date of acquisition? I try with i.spectral but I
>> > don't know how to load an image to the monitor which is
>> > selected to choose a location. Any ideas?
>> >
>> > 4. Why is the newbie forum not active? I mean the link in
>> > the grass webpage doesn't work!
>> >
>> > 5. Once I finish some work related with my studies I would
>> > like to write a practical How-To for absolute beginners.
>> > Are there any kinds of directions?
>> >
>> > Thank you in Advance -- Waiting for helpful hints!
>> >
>> >
>> >
>> > .
>> > Nikos Alexandris - Ph.D. Candidate
>> > .
>> > Department of Remote Sensing
>> > and
>> > Landscape Information Systems
>> > (FeLIS)
>> > .
>> > Faculty of Forestry and Natural Environment
>> > Albert-Ludwigs-University Freiburg
>> > .
>> > Tel. +49 (0) 761 203 3697
>> > Fax. +49 (0) 761 203 3701
>> > Skype: Nikos.Alexandris
>> > .
>> > Address: Tennenbacher str. 4
>> > D-79106 Freiburg i. Br.
>> > Germany
>> > .
>> >
>> > _______________________________________________
>> > grassuser mailing list
>> > grassuser@grass.itc.it
>> > http://grass.itc.it/mailman/listinfo/grassuser
>> >
>> >
>> http://www.nabble.com/file/p13531203/wxgrass-Error.png
>> --
>> View this message in context:
>> http://www.nabble.com/More-QUESTIONS-!--tf4731979.html#a13531203
>> Sent from the Grass - Users mailing list archive at Nabble.com.
>>
>> _______________________________________________
>> grassuser mailing list
>> grassuser@grass.itc.it
>> http://grass.itc.it/mailman/listinfo/grassuser
>>
>
>
> --
> Martin Landa <landa.martin@gmail.com> * http://gama.fsv.cvut.cz/~landa *
>
> _______________________________________________
> grassuser mailing list
> grassuser@grass.itc.it
> http://grass.itc.it/mailman/listinfo/grassuser
>
>

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_______________________________________________
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6

A few replies below

On 11/1/07 8:03 AM, "nikos.alexandris@felis.uni-freiburg.de"
<nikos.alexandris@felis.uni-freiburg.de> wrote:

Hi!

Well... I know that I only have questions (and a lot). Hope
this will change in time...

1. I tried to install wxgrass but I get an error (see
attached screenshot). I followed the steps described in
http://www.les-ejk.cz/english/wxgrass-new-grass-gui-1

Follow the instructions in the README file with wxPython GRASS. IT is the
most up-to-date. Also, AFAIK, it it isn't working on Windows yet.

2. I can't find a How-To install grassaddons for a
beginner? I got some of the extensions (which end in .tgz)
installed with GEM. But I really have a hard time to
install for example i.pr (I really looked almost
everywhere... :expressionless: )

All are different, so I can't help you here. Look for README files with
each addon.

3. Is there a link (image to image) utility so one can
compare pixel-by-pixel 2 images of the region but with a
different date of acquisition? I try with i.spectral but I
don't know how to load an image to the monitor which is
selected to choose a location. Any ideas?

The map calculator (r.mapcalc) is perfect for this. Create a difference map.

r.mapcalc 'diffmap=map1 - map2'

(or pick map calculator from the raster menu)

Then apply the difference color table to the map, using r.colors
(raster->manage map colors->color tables)

4. Why is the newbie forum not active? I mean the link in
the grass webpage doesn't work!

I don't know.

5. Once I finish some work related with my studies I would
like to write a practical How-To for absolute beginners.
Are there any kinds of directions?

GREAT! Put it on the WIKI for all to benefit.

Michael

Thank you in Advance -- Waiting for helpful hints!

                        .
         Nikos Alexandris - Ph.D. Candidate
                        .
            Department of Remote Sensing
                       and
            Landscape Information Systems
                     (FeLIS)
                        .
      Faculty of Forestry and Natural Environment
          Albert-Ludwigs-University Freiburg
                        .
            Tel. +49 (0) 761 203 3697
            Fax. +49 (0) 761 203 3701
             Skype: Nikos.Alexandris
                        .
           Address: Tennenbacher str. 4
              D-79106 Freiburg i. Br.
                     Germany
                        .

__________________________________________
Michael Barton, Professor of Anthropology
Director of Graduate Studies
School of Human Evolution & Social Change
Center for Social Dynamics and Complexity
Arizona State University

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton

7

3. Is there a link (image to image) utility so one can
compare pixel-by-pixel 2 images of the region but with a
different date of acquisition? I try with i.spectral but I
don't know how to load an image to the monitor which is
selected to choose a location. Any ideas?

The map calculator (r.mapcalc) is perfect for this. Create a difference

map.

r.mapcalc 'diffmap=map1 - map2'

(or pick map calculator from the raster menu)

Then apply the difference color table to the map, using r.colors

(raster->manage map colors->color tables)

About this link "tool"... I think my description was not clear enough! I
mean something like the link tool in ERDAS Imagine or in ENVI! Wouldn't it
be useful?

BTW: Thanks to all for the replies. It really gives a good feeling to
beginners to stick-on

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8

Nikos Alexandris wrote:

...
2. I can't find a How-To install grassaddons for a
beginner? I got some of the extensions (which end in .tgz)
installed with GEM. But I really have a hard time to
install for example i.pr (I really looked almost
everywhere... :expressionless: )

This must be definitely improved. You could give us a hand
by starting a Wiki page which then get's improved. For
skilled people here it is often difficult to anticipate
questions from a new-comer - so keep asking! :slight_smile:

Nikos Alexandris wrote:

3. Is there a link (image to image) utility so one can
compare pixel-by-pixel 2 images of the region but with a
different date of acquisition? I try with i.spectral but I
don't know how to load an image to the monitor which is
selected to choose a location. Any ideas?

Pretty easy: d.what.rast is taken multiple input:

d.rast image1
d.what.rast image1,image2,image3[,...]

Nikos Alexandris wrote:

4. Why is the newbie forum not active? I mean the link in
the grass webpage doesn't work!

Which link is that (where?)?

Markus
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9

Thank you very much for the attention.

About a How-To: Once I am ready to prepare something I will do it. In fact,
I already started a work using only open-source and no-fee GIS and Remote
Sensing software.

About the link (pixel-by-pixel comparison): I was not so clear. I meant a
tool like the one that ERDAS Imagine and ENVI offer, so one can link
geographically various data (raster/ vector) for the same region.

About the newbie forum link... http://www.urbeli.com/grassforum/index.php
(It's listed in gdf's GRASS-help page).

Markus Neteler wrote:

Nikos Alexandris wrote:

...
2. I can't find a How-To install grassaddons for a
beginner? I got some of the extensions (which end in .tgz)
installed with GEM. But I really have a hard time to
install for example i.pr (I really looked almost
everywhere... :expressionless: )

This must be definitely improved. You could give us a hand
by starting a Wiki page which then get's improved. For
skilled people here it is often difficult to anticipate
questions from a new-comer - so keep asking! :slight_smile:

Nikos Alexandris wrote:

3. Is there a link (image to image) utility so one can
compare pixel-by-pixel 2 images of the region but with a
different date of acquisition? I try with i.spectral but I
don't know how to load an image to the monitor which is
selected to choose a location. Any ideas?

Pretty easy: d.what.rast is taken multiple input:

d.rast image1
d.what.rast image1,image2,image3[,...]

Nikos Alexandris wrote:

4. Why is the newbie forum not active? I mean the link in
the grass webpage doesn't work!

Which link is that (where?)?

Markus

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10

I still don't understand what you mean by this (I don't use Imagine or
ENVI). Rasters and vectors georeferenced to the same geographic space are by
default linked in the same location/mapset.

Michael

On 11/3/07 3:35 PM, "Nikos Alexandris"
<nikos.alexandris@felis.uni-freiburg.de> wrote:

About the link (pixel-by-pixel comparison): I was not so clear. I meant a
tool like the one that ERDAS Imagine and ENVI offer, so one can link
geographically various data (raster/ vector) for the same region.

__________________________________________
Michael Barton, Professor of Anthropology
Director of Graduate Studies
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton

11

Please excuse me for my "poor" descriptions before.

The kinf of "Link" tool:
ENVI, and ERDAS as well, provide a "Link" tool with which one can open,
side-by-side, images of the same region and while panning, zooming or
resizing one of the images, these actions are automatically mirrored to the
othe image.

Why is this useful:
I provide a (small) screenshot to illustrate my need (!). In this example I
try to visually interpret the land cover on the image which is on the right
(it is a SPOT4 acquisition). To support this task, whenever it is difficult
to recognize something, I use the orthophotos (in my screenshot located on
the left side). The tool is capable to link multiple images with the same or
different resolution, with the pre-condition that they are georeferenced

(In this example the object of interest is a small football(soccer!)
stadium... !)

.
Again... I am just putting questions... I think, in most cases, asking
doesn't hurt.
Is there an alternative way to replace this method (supporting a visual
interpretation with ancillary data)? Would it be very difficult to implement
something like that?

Thank you,
Nikos.

Michael Barton wrote:

I still don't understand what you mean by this (I don't use Imagine or
ENVI). Rasters and vectors georeferenced to the same geographic space are
by
default linked in the same location/mapset.

Michael

On 11/3/07 3:35 PM, "Nikos Alexandris"
<nikos.alexandris@felis.uni-freiburg.de> wrote:

About the link (pixel-by-pixel comparison): I was not so clear. I meant a
tool like the one that ERDAS Imagine and ENVI offer, so one can link
geographically various data (raster/ vector) for the same region.

__________________________________________
Michael Barton, Professor of Anthropology
Director of Graduate Studies
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton

_______________________________________________
grassuser mailing list
grassuser@grass.itc.it
http://grass.itc.it/mailman/listinfo/grassuser

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12

On 04/11/07 10:24, Nikos Alexandris wrote:

Please excuse me for my "poor" descriptions before.

The kinf of "Link" tool:
ENVI, and ERDAS as well, provide a "Link" tool with which one can open,
side-by-side, images of the same region and while panning, zooming or
resizing one of the images, these actions are automatically mirrored to the
othe image.

[...]

Is there an alternative way to replace this method (supporting a visual
interpretation with ancillary data)? Would it be very difficult to implement
something like that?

There is no such linking tool in GRASS. However, what you can do (in the GIS Manager) is zoom to your desired region in one window, then (in the Map Display window) "Set current region to match display". You can then "Zoom to current region" in the other Map Display windows.

Or if you work with old-style monitors, zoom to desired region in one monitor, then 'd.mon select' & 'd.redraw' in the others.

Moritz

13

A long time ago (2003) I asked the same question about linking monitors!
The tread is here:
http://www.nabble.com/-GRASSLIST%3A5609--Linking-Monitors-tf3101985.html#a8608876

John Gillette came up with a nice script to do this using two display
monitors, x0 and x1.
Drawbacks:
1. You must use the old monitors, not a big problem I think
2. You must execute the script every time for each pan or zoom
3. Only one movement por script run (one pan or one zoom)

Maybe there is a way to implement this using the new displays...
To use the old x displays, go to the grass command line and issue:
d.mon start x0
d.mon start x1
This will start the monitors
To select the monitor to use issue:
d.mon select=x0
d.erase erases the monitor
d.rast map=your_map draws on the monitor

Good luck :slight_smile:
Daniel

The original message by John Gillette follows:
---------------------------------------------------------------------------------
[GRASSLIST:5636] Linking Monitors script Click to flag this post

by John Gillette Feb 21, 2003; 05:50pm ::

try this:

Select and then Erase x1 and then display what ever you want there.
Select x0 and erase and display other info there.

Run this script to either pan or zoom in x0. After finishing
the pan or zoom x1 will redraw it's contents at the same region
thereby "following" what ever is done in x0.

The disadvantage is that you can only do 1 pan or zoom at a time,
i.e. not interactively.

usage:

script_name z <- does zoom instead of pan
script_name

zooming and panning in x0. x0 is selected at exit.

Does this help?

John

------------------
#!/bin/sh

d.mon select=x1
monitor1=`d.save -o`

d.mon select=x0
if [ "$1" = "z" ]
then
   d.zoom
else
   d.pan
fi
region=`g.region -g`

d.mon select=x1
d.erase
g.region $region
eval "$monitor1"

d.mon select=x0

exit 0

On Nov 5, 2007 7:39 AM, Moritz Lennert <mlennert@club.worldonline.be> wrote:

On 04/11/07 10:24, Nikos Alexandris wrote:
> Please excuse me for my "poor" descriptions before.
>
> The kinf of "Link" tool:
> ENVI, and ERDAS as well, provide a "Link" tool with which one can open,
> side-by-side, images of the same region and while panning, zooming or
> resizing one of the images, these actions are automatically mirrored to the
> othe image.

[...]

> Is there an alternative way to replace this method (supporting a visual
> interpretation with ancillary data)? Would it be very difficult to implement
> something like that?
>

There is no such linking tool in GRASS. However, what you can do (in the
GIS Manager) is zoom to your desired region in one window, then (in the
Map Display window) "Set current region to match display". You can then
"Zoom to current region" in the other Map Display windows.

Or if you work with old-style monitors, zoom to desired region in one
monitor, then 'd.mon select' & 'd.redraw' in the others.

Moritz

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14

Thank you!

I am checking on it...

Daniel Victoria wrote:

A long time ago (2003) I asked the same question about linking monitors!
The tread is here:
http://www.nabble.com/-GRASSLIST%3A5609--Linking-Monitors-tf3101985.html#a8608876

John Gillette came up with a nice script to do this using two display
monitors, x0 and x1.
Drawbacks:
1. You must use the old monitors, not a big problem I think
2. You must execute the script every time for each pan or zoom
3. Only one movement por script run (one pan or one zoom)

Maybe there is a way to implement this using the new displays...
To use the old x displays, go to the grass command line and issue:
d.mon start x0
d.mon start x1
This will start the monitors
To select the monitor to use issue:
d.mon select=x0
d.erase erases the monitor
d.rast map=your_map draws on the monitor

Good luck :slight_smile:
Daniel

The original message by John Gillette follows:
---------------------------------------------------------------------------------
[GRASSLIST:5636] Linking Monitors script Click to flag this post

by John Gillette Feb 21, 2003; 05:50pm ::

try this:

Select and then Erase x1 and then display what ever you want there.
Select x0 and erase and display other info there.

Run this script to either pan or zoom in x0. After finishing
the pan or zoom x1 will redraw it's contents at the same region
thereby "following" what ever is done in x0.

The disadvantage is that you can only do 1 pan or zoom at a time,
i.e. not interactively.

usage:

script_name z <- does zoom instead of pan
script_name

zooming and panning in x0. x0 is selected at exit.

Does this help?

John

------------------
#!/bin/sh

d.mon select=x1
monitor1=`d.save -o`

d.mon select=x0
if [ "$1" = "z" ]
then
   d.zoom
else
   d.pan
fi
region=`g.region -g`

d.mon select=x1
d.erase
g.region $region
eval "$monitor1"

d.mon select=x0

exit 0

On Nov 5, 2007 7:39 AM, Moritz Lennert <mlennert@club.worldonline.be>
wrote:

On 04/11/07 10:24, Nikos Alexandris wrote:
> Please excuse me for my "poor" descriptions before.
>
> The kinf of "Link" tool:
> ENVI, and ERDAS as well, provide a "Link" tool with which one can open,
> side-by-side, images of the same region and while panning, zooming or
> resizing one of the images, these actions are automatically mirrored to
the
> othe image.

[...]

> Is there an alternative way to replace this method (supporting a visual
> interpretation with ancillary data)? Would it be very difficult to
implement
> something like that?
>

There is no such linking tool in GRASS. However, what you can do (in the
GIS Manager) is zoom to your desired region in one window, then (in the
Map Display window) "Set current region to match display". You can then
"Zoom to current region" in the other Map Display windows.

Or if you work with old-style monitors, zoom to desired region in one
monitor, then 'd.mon select' & 'd.redraw' in the others.

Moritz

_______________________________________________
grassuser mailing list
grassuser@grass.itc.it
http://grass.itc.it/mailman/listinfo/grassuser

_______________________________________________
grassuser mailing list
grassuser@grass.itc.it
http://grass.itc.it/mailman/listinfo/grassuser

--
View this message in context: http://www.nabble.com/More-QUESTIONS-!--tf4731979.html#a13589468
Sent from the Grass - Users mailing list archive at Nabble.com.

15

Nikos Alexandris wrote:

The kinf of "Link" tool:
ENVI, and ERDAS as well, provide a "Link" tool with which one can open,
side-by-side, images of the same region and while panning, zooming or
resizing one of the images, these actions are automatically mirrored to the
othe image.

Why is this useful:
I provide a (small) screenshot to illustrate my need (!). In this example I
try to visually interpret the land cover on the image which is on the right
(it is a SPOT4 acquisition). To support this task, whenever it is difficult
to recognize something, I use the orthophotos (in my screenshot located on
the left side). The tool is capable to link multiple images with the same or
different resolution, with the pre-condition that they are georeferenced

(In this example the object of interest is a small football(soccer!)
stadium... !)

.
Again... I am just putting questions... I think, in most cases, asking
doesn't hurt.
Is there an alternative way to replace this method (supporting a visual
interpretation with ancillary data)? Would it be very difficult to implement
something like that?

perhaps in the GIS manager overlay the two raster images with transparency set
for the top one.

or in a xmonitor from the command line use d.shadedmap or d.his to overlay the
images with transparency.

see also the "cross hatch" trick shown in the GRASS Book to interleave the two
images in one display without transparency.

Hamish

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16

Nikos Alexandris wrote:

The kinf of "Link" tool:
ENVI, and ERDAS as well, provide a "Link" tool with which one can open,
side-by-side, images of the same region and while panning, zooming or
resizing one of the images, these actions are automatically mirrored to the
othe image.

oh, I forgot to mention to try d.frame if using xmons from the command line.
(see the d.split module or d.frame.quarter from the wiki addons)
you need to d.redraw explicitly in each frame after changing the zoom region.

Hamish

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