[GRASSGUI] Re: r.mapcalc

[Michael Barton]

What kind of results are you hoping to get in the end? You say you want to
do line-of-sight analysis. It is increasingly unclear to me what are the
specific outcomes you are looking for: whether your x2y2 point is visible
from x1y1? a map of the cells between x1y1 and x2y2 that are visible when
you look from x1y1 to x2y2? something else? Running r.profile on a r.los map
that you have reclassified to binary would ID the visible cells between x1y1
and x2y2. You can visually tell if x2y2 is visible from x1y1. I can't tell
what you are trying to do.

Michael

hi,
i want tyo find a line of site between two co-ordinates x1,y1 to x2,y2
then i wrote r.reclass input=map outpuy=mapout

then i specified two co-rdinates for two points

but not able to get the output
culd you tell me how to write using x1y1 and x2y2
plz
Use reclassify interactively or recode interactively from the menu. Put the

name of the file you want to reclassify (for integers) or recode (for
floating point values) in the entry box. You'll need to specify and output
file too.
Then enter your rules into the text box below and click "apply" or "run".
You'll need to know what the values are for your line (between point of
observer and what you want to see).
line value min:line value max:1:1
rest value min:rest value max:0:0
[line value min] thru [line value max] = 1
* = 0
Michael

hi,
can you tell me how to fill up that:help says
Map type conversion
To simply convert a raster between formats (eg. int to float) the user would
use the first argument. For example
10:1500:0.1:15.0
would convert an old raster with range between 10 and 1500 to a float raster
with range bewteen 0.1 and 15.0.
Value replacement
r.recode can be used to replace existing cell values by others. The
formatting
is as described above. In following example the values 1, 2 and 3 are
replaced
r.recode in=oldmap out=newmap << EOF
1:1:1.1:1.1
2:2:7.5:7.5
3:3:0.4:0.4
EOF
1. I have a dgn vector map which i have convetred it into raster
2. Now for finding line of sight i will take say two points..one with name
"a"
and another name"b" now how will i reclass or recode the values..and what
dose
this value actually mean?
plz support me >
Jainita,

Create a map with the line of sight you want to analyze. Reclassify it
(r.reclass or r.recode) to make the cells in the line you want to analyze 1
and the rest of the cells 0.
Michael

Hi,
thank you for yr advice butcan you tell me how to prepare this binary file
Thanks,
jainita>
Jainita,

Use the binary map setting to specify the area you want to do visibility
analysis for. It should be 1 where you want visibility/los calcuations
and
0
where you don't want this calculated.
Michael

Hi,I tried with r.los but it gives visibility all over i.e in 360degree
for
the distance specified.
But I want only between two points in a line i.e not 360 degree so can
you
help me with it.
I would be really oblige if you help me since I am racking my mail a lot
on
this and still unable to find the solution
Thanking you once again
-----Original Message-----
Sent: Wednesday, October 17, 2007 7:59 PM
Subject: Re: r.mapcalc
Use r.los for line of site calculations.
Michael

hi,
i am working on grass and want to know how r.mapcalc can be used for
calculation of pat_map/mask.
syntax says---------------r.mapcalc pat)mkap="if(where_you_want,1, 0)"
for
creating a map which can be used to calcualte line of sight between two

points

can anyone elaborate on it with an eg:say i want to know what all is
beign
seen between any two co-ordinate in map.
Please help,i am doing for the first time
Thanking You,
Jainita

__________________________________________
Michael Barton, Professor of Anthropology
Director of Graduate Studies
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University
phone: [phone]
fax: [phone]
www: http://www.public.asu.edu/~cmbarton

__________________________________________
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: [phone]
fax: [phone]
www: http://www.public.asu.edu/~cmbarton

__________________________________________
Michael Barton, Professor of Anthropology
Director of Graduate Studies
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University
phone: [phone]
fax: [phone]
www: http://www.public.asu.edu/~cmbarton

__________________________________________
Michael Barton, Professor of Anthropology
Director of Graduate Studies
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University
phone: [phone]
fax: [phone]
www: http://www.public.asu.edu/~cmbarton

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

phone: [phone]
fax: [phone]
www: http://www.public.asu.edu/~cmbarton