[GRASS-user] Understanding Raster Map Input Files

GRASS GRASS user
1

Hi all,
I’m currently doing my research on wildfire behavior modeling. For that purpose, I’m using the wildfire behavior module in GRASS GIS. I came up with these problems in understanding the sample raster map files provided by GRASS GIS. The content is as follows,

File 01: 1hour_moisture

15 categories ---------------------------------------------------> (1)

1 Hour Fuel Moisture of Bass River Fire of 1977 ------> (2)

0.00 0.00 0.00 0.00 -----------------------------------------------> (3)
0:no data -------------------------------------------------------------> (4)
3:3 % ------------------------------------------------------------------> (5)
15:15 % --------------------------------------------------------------> (6)

Can you explain (1) to (6)

File 02: fire_origin

1 categories -----------------------------------------------------> (7)

Map of Fire Origin of Bass River Fire --------------------> (8)

0.00 0.00 0.00 0.00 ---------------------------------------------> (9)
0:no data -----------------------------------------------------------> (10)
1:fire origin ---------------------------------------------------------> (11)

Well, also (7) to (11)

Have a nice day guys! cheers!!

BR,
Vidura Dantanarayana.

2

Hi all,

We also encountered the same problem as mentioned here by Vidura. Those data inside the wildfire data files are hard to understand. The structure cannot be identified clearly such that what’s meant by those data is also unclear.

As we found @Vaclav Petras has done a research paper on this module. And we think this part is also added to the Grass from him
If he is seeing this Can you please explain this.

Thank you
Best regards.

On Tue, 21 Aug 2018 at 19:08, Vidura Dantanarayana <vidurada@gmail.com> wrote:

Hi all,
I’m currently doing my research on wildfire behavior modeling. For that purpose, I’m using the wildfire behavior module in GRASS GIS. I came up with these problems in understanding the sample raster map files provided by GRASS GIS. The content is as follows,

File 01: 1hour_moisture

15 categories ---------------------------------------------------> (1)

1 Hour Fuel Moisture of Bass River Fire of 1977 ------> (2)

0.00 0.00 0.00 0.00 -----------------------------------------------> (3)
0:no data -------------------------------------------------------------> (4)
3:3 % ------------------------------------------------------------------> (5)
15:15 % --------------------------------------------------------------> (6)

Can you explain (1) to (6)

File 02: fire_origin

1 categories -----------------------------------------------------> (7)

Map of Fire Origin of Bass River Fire --------------------> (8)

0.00 0.00 0.00 0.00 ---------------------------------------------> (9)
0:no data -----------------------------------------------------------> (10)
1:fire origin ---------------------------------------------------------> (11)

Well, also (7) to (11)

Have a nice day guys! cheers!!

BR,
Vidura Dantanarayana.

grass-user mailing list
grass-user@lists.osgeo.org
https://lists.osgeo.org/mailman/listinfo/grass-user

3

On 21/08/18 15:38, Vidura Dantanarayana wrote:

Hi all,
I'm currently doing my research on wildfire behavior modeling. For that purpose, I'm using the wildfire behavior module in GRASS GIS. I came up with these problems in understanding the sample raster map files provided by GRASS GIS. The content is as follows,

File 01: 1hour_moisture

# 15 categories ---------------------------------------------------> (1)
1 Hour Fuel Moisture of Bass River Fire of 1977 ------> (2)

0.00 0.00 0.00 0.00 -----------------------------------------------> (3)
0:no data -------------------------------------------------------------> (4)
3:3 % ------------------------------------------------------------------> (5)
15:15 % --------------------------------------------------------------> (6)

Can you explain (1) to (6)

File 02: fire_origin

# 1 categories -----------------------------------------------------> (7)
Map of Fire Origin of Bass River Fire --------------------> (8)

0.00 0.00 0.00 0.00 ---------------------------------------------> (9)
0:no data -----------------------------------------------------------> (10)
1:fire origin ---------------------------------------------------------> (11)

Well, also (7) to (11)

The fire demo data comes in a ready-made GRASS location formation. The easiest way to use it is to create a directory (traditionally called "GRASSDATA", but you can chose any name you like) and to decompress the contents of the fire_grass6data.tar.gz into that directory. You can then launch GRASS GIS, pointing it to the demolocation and the demomapset.

The information you mention above comes from internal files of the GRASS Database which contain the category and category labels information. You do not need to understand these internal formats (part of the GRASS raster format which is organized in a series of files). Generally, you should never have to actually go into the GRASS database, i.e. the directory where GRASS stores its data, to get information from files. You should rather access this information via the relevant modules.

For example you can see the same information using r.category:

r.category 1hour_moisture
3 3 %
15 15 %

which means that two categories are identified for this file: 3, which is labeled '3%' and 15 which is labeled '15%'.

Using, for example, r.stats you can see how many pixels of the map are in each category:

r.stats -c 1hour_moisture --q
3 27139
15 3098
* 48163

(* representing NULL pixels which don't contain a value).

Moritz

4

Hi Vidura,

First of all, please keep discussions on the list.

On 31/08/18 09:48, Vidura Dantanarayana wrote:

Hi Moritz,

Really appreciate your help as we are facing this problem for some days now. First I'm a beginner user. Can you explain what are the categories and how those used in GRASS GIS?

GRASS GIS is an extremely wonderful and powerful tool, but it does need some initial learning in order to understand how to use it. Just answering the questions below will not provide that for you.

I would suggest that you go through some of the basic introductory material, just in order to get a feeling for GRASS GIS, before attacking your specific problem.

You could have a look at the following resources (at least for their introductory parts):

- https://grass.osgeo.org/grass74/manuals/helptext.html
- https://grass.osgeo.org/grass74/manuals/rasterintro.html
- https://grass.osgeo.org/grass74/manuals/vectorintro.html
- https://grasswiki.osgeo.org/wiki/From_GRASS_GIS_novice_to_power_user_(workshop_at_FOSS4G_Boston_2017)
- http://www.training.gismentors.eu/isprs-summer-school-2016/lesson1/grass-gis.html

Or search for "GRASS GIS" in YouTube for some videos.

Let's say I need to create custom 1hour_moisture (or any other file), so how can I create these files?

How you create these files depends on the data that you have as input.

If you look at the metadata of the file in the demolocation (right-click->Metadata or 'r.info 1hour_moisture' you will this information at the end:

| Data Description: |
| generated by r.mapcalc |
| |
| Comments: |
| if(fuel_class==4,3,if(fuel_class==8,15))

This means that the authors had a raster file called 'fuel_class' and used the raster calculator (r.mapcalc) to reclass that file attributing the value 3 to those pixels who had class=4 in the original map and value 15 to pixels with class=8.

I have no idea what this original map contained, so cannot help you further (I don't know much about fire spread modeling).

Can you look at the following problem again?

# 1 categories -----------------------------------------------------> (1)
Map of Fire Origin of Bass River Fire --------------------> (2)

0.00 0.00 0.00 0.00 ---------------------------------------------> (3)
0:no data -----------------------------------------------------------> (4)
1:fire origin ---------------------------------------------------------> (5)

I need to know how to customize the location of origin. I mean, I want to ignite the fire from another place rather the place specified in demo data.

If you have the origin location as coordinates, you can create a vector point at the location using v.in.ascii: in the GUI of that module you can enter coordinates interactively. Then you convert the map to a raster map using v.to.rast.

Moritz

5

Hi all,

Thank you very much Moritz Lennert for the explanation and apologize for the mistake I’ve done. I will try what you suggest by myself. Hope It’s okay to questioning again if I found a problem again. Have a wonderful day. Cheers!!!

BR,
Vidura Dantanarayana.

On Sat, Sep 1, 2018 at 2:04 AM Moritz Lennert <mlennert@club.worldonline.be> wrote:

Hi Vidura,

First of all, please keep discussions on the list.

On 31/08/18 09:48, Vidura Dantanarayana wrote:

Hi Moritz,

Really appreciate your help as we are facing this problem for some days
now. First I’m a beginner user. Can you explain what are the categories
and how those used in GRASS GIS?

GRASS GIS is an extremely wonderful and powerful tool, but it does need
some initial learning in order to understand how to use it. Just
answering the questions below will not provide that for you.

I would suggest that you go through some of the basic introductory
material, just in order to get a feeling for GRASS GIS, before attacking
your specific problem.

You could have a look at the following resources (at least for their
introductory parts):

https://grasswiki.osgeo.org/wiki/From_GRASS_GIS_novice_to_power_user_(workshop_at_FOSS4G_Boston_2017)

http://www.training.gismentors.eu/isprs-summer-school-2016/lesson1/grass-gis.html

Or search for “GRASS GIS” in YouTube for some videos.

Let’s say I need to create custom
1hour_moisture (or any other file), so how can I create these files?

How you create these files depends on the data that you have as input.

If you look at the metadata of the file in the demolocation
(right-click->Metadata or ‘r.info 1hour_moisture’ you will this
information at the end:

| Data Description:
|
| generated by r.mapcalc
|
|
|
| Comments:
|
| if(fuel_class==4,3,if(fuel_class==8,15))

This means that the authors had a raster file called ‘fuel_class’ and
used the raster calculator (r.mapcalc) to reclass that file attributing
the value 3 to those pixels who had class=4 in the original map and
value 15 to pixels with class=8.

I have no idea what this original map contained, so cannot help you
further (I don’t know much about fire spread modeling).

Can
you look at the following problem again?

1 categories -----------------------------------------------------> (1)

Map of Fire Origin of Bass River Fire --------------------> (2)

0.00 0.00 0.00 0.00 ---------------------------------------------> (3)
0:no data -----------------------------------------------------------> (4)
1:fire origin ---------------------------------------------------------> (5)

I need to know how to customize the location of origin. I mean, I want
to ignite the fire from another place rather the place specified in demo
data.

If you have the origin location as coordinates, you can create a vector
point at the location using v.in.ascii: in the GUI of that module you
can enter coordinates interactively. Then you convert the map to a
raster map using v.to.rast.

Moritz

6

Hi Vidura,

You need to prepare the input data to r.ros algorithm

https://grass.osgeo.org/grass74/manuals/r.ros.html

The input data needs to be in raster format.

First you need to use the standard NFFL 13 fuel models system (https://www.fs.fed.us/rm/pubs/rmrs_gtr153.pdf) as fuel model input raster.

You also need the fuel moisture content for all sizes and response times (dead 1h, 10h, 100h and live), in percentage.

As Moritz explained to you, you can see that the 1hour_moisture raster of the sample data is composed by:

  • 3% moisture in areas of fuel model 4;
  • 15% moisture in areas of fuel model 8.

You can give homogeneous fuel moisture content for each response times, or different if you have that information, like in the sample data.

Then you need an elevation raster (DEM), calculate slope and aspect (if you don’t have them yet, with r.slope.aspect), and a raster with wind speed (in feet/minute) and another with wind direction (clockwise from north, in degrees).

With this data, you run r.ros and with the output rasters, run r.spread

https://grass.osgeo.org/grass74/manuals/r.spread.html

r.spread just need the an additional raster, with the ignition(s)/starting sources. Pixels of starting sources raster needs to be only values of 1 (ignition points/areas) and 0 (other areas). If you have the ignitions in vector format, just use v.to.rast.

I hope this helps.

Best regards,
Pedro Venâncio

Vidura Dantanarayana <vidurada@gmail.com> escreveu no dia sábado, 1/09/2018 à(s) 14:12:

Hi all,

Thank you very much Moritz Lennert for the explanation and apologize for the mistake I’ve done. I will try what you suggest by myself. Hope It’s okay to questioning again if I found a problem again. Have a wonderful day. Cheers!!!

BR,
Vidura Dantanarayana.

On Sat, Sep 1, 2018 at 2:04 AM Moritz Lennert <mlennert@club.worldonline.be> wrote:

Hi Vidura,

First of all, please keep discussions on the list.

On 31/08/18 09:48, Vidura Dantanarayana wrote:

Hi Moritz,

Really appreciate your help as we are facing this problem for some days
now. First I’m a beginner user. Can you explain what are the categories
and how those used in GRASS GIS?

GRASS GIS is an extremely wonderful and powerful tool, but it does need
some initial learning in order to understand how to use it. Just
answering the questions below will not provide that for you.

I would suggest that you go through some of the basic introductory
material, just in order to get a feeling for GRASS GIS, before attacking
your specific problem.

You could have a look at the following resources (at least for their
introductory parts):

https://grasswiki.osgeo.org/wiki/From_GRASS_GIS_novice_to_power_user_(workshop_at_FOSS4G_Boston_2017)

http://www.training.gismentors.eu/isprs-summer-school-2016/lesson1/grass-gis.html

Or search for “GRASS GIS” in YouTube for some videos.

Let’s say I need to create custom
1hour_moisture (or any other file), so how can I create these files?

How you create these files depends on the data that you have as input.

If you look at the metadata of the file in the demolocation
(right-click->Metadata or ‘r.info 1hour_moisture’ you will this
information at the end:

| Data Description:
|
| generated by r.mapcalc
|
|
|
| Comments:
|
| if(fuel_class==4,3,if(fuel_class==8,15))

This means that the authors had a raster file called ‘fuel_class’ and
used the raster calculator (r.mapcalc) to reclass that file attributing
the value 3 to those pixels who had class=4 in the original map and
value 15 to pixels with class=8.

I have no idea what this original map contained, so cannot help you
further (I don’t know much about fire spread modeling).

Can
you look at the following problem again?

1 categories -----------------------------------------------------> (1)

Map of Fire Origin of Bass River Fire --------------------> (2)

0.00 0.00 0.00 0.00 ---------------------------------------------> (3)
0:no data -----------------------------------------------------------> (4)
1:fire origin ---------------------------------------------------------> (5)

I need to know how to customize the location of origin. I mean, I want
to ignite the fire from another place rather the place specified in demo
data.

If you have the origin location as coordinates, you can create a vector
point at the location using v.in.ascii: in the GUI of that module you
can enter coordinates interactively. Then you convert the map to a
raster map using v.to.rast.

Moritz

grass-user mailing list
grass-user@lists.osgeo.org
https://lists.osgeo.org/mailman/listinfo/grass-user

7

Hi Pedro,

Thank you very much for the explanation. That helped me to get a basic idea of what these files do. Then what I did was to change these files. I changed some records in wind speed and wind direction (the files in demomapset/cats). But what I observed was there was no change in the shape of spread even after the alterations. Is there anyone who willing to help me in crating custom files if I provide the relevent information. I need to crate wind, moisture, and fire origin files.

BR,
Vidura Dantanarayana.

On Sat, Sep 1, 2018 at 7:23 PM Pedro Venâncio <pedrongvenancio@gmail.com> wrote:

Hi Vidura,

You need to prepare the input data to r.ros algorithm

https://grass.osgeo.org/grass74/manuals/r.ros.html

The input data needs to be in raster format.

First you need to use the standard NFFL 13 fuel models system (https://www.fs.fed.us/rm/pubs/rmrs_gtr153.pdf) as fuel model input raster.

You also need the fuel moisture content for all sizes and response times (dead 1h, 10h, 100h and live), in percentage.

As Moritz explained to you, you can see that the 1hour_moisture raster of the sample data is composed by:

  • 3% moisture in areas of fuel model 4;
  • 15% moisture in areas of fuel model 8.

You can give homogeneous fuel moisture content for each response times, or different if you have that information, like in the sample data.

Then you need an elevation raster (DEM), calculate slope and aspect (if you don’t have them yet, with r.slope.aspect), and a raster with wind speed (in feet/minute) and another with wind direction (clockwise from north, in degrees).

With this data, you run r.ros and with the output rasters, run r.spread

https://grass.osgeo.org/grass74/manuals/r.spread.html

r.spread just need the an additional raster, with the ignition(s)/starting sources. Pixels of starting sources raster needs to be only values of 1 (ignition points/areas) and 0 (other areas). If you have the ignitions in vector format, just use v.to.rast.

I hope this helps.

Best regards,
Pedro Venâncio

Vidura Dantanarayana <vidurada@gmail.com> escreveu no dia sábado, 1/09/2018 à(s) 14:12:

Hi all,

Thank you very much Moritz Lennert for the explanation and apologize for the mistake I’ve done. I will try what you suggest by myself. Hope It’s okay to questioning again if I found a problem again. Have a wonderful day. Cheers!!!

BR,
Vidura Dantanarayana.

On Sat, Sep 1, 2018 at 2:04 AM Moritz Lennert <mlennert@club.worldonline.be> wrote:

Hi Vidura,

First of all, please keep discussions on the list.

On 31/08/18 09:48, Vidura Dantanarayana wrote:

Hi Moritz,

Really appreciate your help as we are facing this problem for some days
now. First I’m a beginner user. Can you explain what are the categories
and how those used in GRASS GIS?

GRASS GIS is an extremely wonderful and powerful tool, but it does need
some initial learning in order to understand how to use it. Just
answering the questions below will not provide that for you.

I would suggest that you go through some of the basic introductory
material, just in order to get a feeling for GRASS GIS, before attacking
your specific problem.

You could have a look at the following resources (at least for their
introductory parts):

https://grasswiki.osgeo.org/wiki/From_GRASS_GIS_novice_to_power_user_(workshop_at_FOSS4G_Boston_2017)

http://www.training.gismentors.eu/isprs-summer-school-2016/lesson1/grass-gis.html

Or search for “GRASS GIS” in YouTube for some videos.

Let’s say I need to create custom
1hour_moisture (or any other file), so how can I create these files?

How you create these files depends on the data that you have as input.

If you look at the metadata of the file in the demolocation
(right-click->Metadata or ‘r.info 1hour_moisture’ you will this
information at the end:

| Data Description:
|
| generated by r.mapcalc
|
|
|
| Comments:
|
| if(fuel_class==4,3,if(fuel_class==8,15))

This means that the authors had a raster file called ‘fuel_class’ and
used the raster calculator (r.mapcalc) to reclass that file attributing
the value 3 to those pixels who had class=4 in the original map and
value 15 to pixels with class=8.

I have no idea what this original map contained, so cannot help you
further (I don’t know much about fire spread modeling).

Can
you look at the following problem again?

1 categories -----------------------------------------------------> (1)

Map of Fire Origin of Bass River Fire --------------------> (2)

0.00 0.00 0.00 0.00 ---------------------------------------------> (3)
0:no data -----------------------------------------------------------> (4)
1:fire origin ---------------------------------------------------------> (5)

I need to know how to customize the location of origin. I mean, I want
to ignite the fire from another place rather the place specified in demo
data.

If you have the origin location as coordinates, you can create a vector
point at the location using v.in.ascii: in the GUI of that module you
can enter coordinates interactively. Then you convert the map to a
raster map using v.to.rast.

Moritz

grass-user mailing list
grass-user@lists.osgeo.org
https://lists.osgeo.org/mailman/listinfo/grass-user

8

Hi Vidura,

Just like Moritz said, you need to start by the basics about GRASS.

That said, it is better to create new raster layers than change the existing ones.

To test other wind speed and direction, moisture, etc, just create new rasters with r.mapcalc

https://grass.osgeo.org/grass74/manuals/r.mapcalc.html

Start with constant rasters, using the example in the r.mapcalc manual.

Best regards,
Pedro Venâncio

A seg, 3/09/2018, 06:22, Vidura Dantanarayana <vidurada@gmail.com> escreveu:

Hi Pedro,

Thank you very much for the explanation. That helped me to get a basic idea of what these files do. Then what I did was to change these files. I changed some records in wind speed and wind direction (the files in demomapset/cats). But what I observed was there was no change in the shape of spread even after the alterations. Is there anyone who willing to help me in crating custom files if I provide the relevent information. I need to crate wind, moisture, and fire origin files.

BR,
Vidura Dantanarayana.

On Sat, Sep 1, 2018 at 7:23 PM Pedro Venâncio <pedrongvenancio@gmail.com> wrote:

Hi Vidura,

You need to prepare the input data to r.ros algorithm

https://grass.osgeo.org/grass74/manuals/r.ros.html

The input data needs to be in raster format.

First you need to use the standard NFFL 13 fuel models system (https://www.fs.fed.us/rm/pubs/rmrs_gtr153.pdf) as fuel model input raster.

You also need the fuel moisture content for all sizes and response times (dead 1h, 10h, 100h and live), in percentage.

As Moritz explained to you, you can see that the 1hour_moisture raster of the sample data is composed by:

  • 3% moisture in areas of fuel model 4;
  • 15% moisture in areas of fuel model 8.

You can give homogeneous fuel moisture content for each response times, or different if you have that information, like in the sample data.

Then you need an elevation raster (DEM), calculate slope and aspect (if you don’t have them yet, with r.slope.aspect), and a raster with wind speed (in feet/minute) and another with wind direction (clockwise from north, in degrees).

With this data, you run r.ros and with the output rasters, run r.spread

https://grass.osgeo.org/grass74/manuals/r.spread.html

r.spread just need the an additional raster, with the ignition(s)/starting sources. Pixels of starting sources raster needs to be only values of 1 (ignition points/areas) and 0 (other areas). If you have the ignitions in vector format, just use v.to.rast.

I hope this helps.

Best regards,
Pedro Venâncio

Vidura Dantanarayana <vidurada@gmail.com> escreveu no dia sábado, 1/09/2018 à(s) 14:12:

Hi all,

Thank you very much Moritz Lennert for the explanation and apologize for the mistake I’ve done. I will try what you suggest by myself. Hope It’s okay to questioning again if I found a problem again. Have a wonderful day. Cheers!!!

BR,
Vidura Dantanarayana.

On Sat, Sep 1, 2018 at 2:04 AM Moritz Lennert <mlennert@club.worldonline.be> wrote:

Hi Vidura,

First of all, please keep discussions on the list.

On 31/08/18 09:48, Vidura Dantanarayana wrote:

Hi Moritz,

Really appreciate your help as we are facing this problem for some days
now. First I’m a beginner user. Can you explain what are the categories
and how those used in GRASS GIS?

GRASS GIS is an extremely wonderful and powerful tool, but it does need
some initial learning in order to understand how to use it. Just
answering the questions below will not provide that for you.

I would suggest that you go through some of the basic introductory
material, just in order to get a feeling for GRASS GIS, before attacking
your specific problem.

You could have a look at the following resources (at least for their
introductory parts):

https://grasswiki.osgeo.org/wiki/From_GRASS_GIS_novice_to_power_user_(workshop_at_FOSS4G_Boston_2017)

http://www.training.gismentors.eu/isprs-summer-school-2016/lesson1/grass-gis.html

Or search for “GRASS GIS” in YouTube for some videos.

Let’s say I need to create custom
1hour_moisture (or any other file), so how can I create these files?

How you create these files depends on the data that you have as input.

If you look at the metadata of the file in the demolocation
(right-click->Metadata or ‘r.info 1hour_moisture’ you will this
information at the end:

| Data Description:
|
| generated by r.mapcalc
|
|
|
| Comments:
|
| if(fuel_class==4,3,if(fuel_class==8,15))

This means that the authors had a raster file called ‘fuel_class’ and
used the raster calculator (r.mapcalc) to reclass that file attributing
the value 3 to those pixels who had class=4 in the original map and
value 15 to pixels with class=8.

I have no idea what this original map contained, so cannot help you
further (I don’t know much about fire spread modeling).

Can
you look at the following problem again?

1 categories -----------------------------------------------------> (1)

Map of Fire Origin of Bass River Fire --------------------> (2)

0.00 0.00 0.00 0.00 ---------------------------------------------> (3)
0:no data -----------------------------------------------------------> (4)
1:fire origin ---------------------------------------------------------> (5)

I need to know how to customize the location of origin. I mean, I want
to ignite the fire from another place rather the place specified in demo
data.

If you have the origin location as coordinates, you can create a vector
point at the location using v.in.ascii: in the GUI of that module you
can enter coordinates interactively. Then you convert the map to a
raster map using v.to.rast.

Moritz

grass-user mailing list
grass-user@lists.osgeo.org
https://lists.osgeo.org/mailman/listinfo/grass-user

9

Hi Pedro,

Thank you for the reply and it helped me a lot. So here what I did. I needed to create the raster file such wind speed is 230 ft/min. So I used the following command.

r.mapcalc “new_wind_speed = 350”

Then I run the fire behavior module and observed the changing of the spread. Did the same procedure for wind direction.

r.mapcalc “new_wind_direction = 50”

I want to know that whether what I did was correct and is it the right way to create input raster file.

BR,
Vidura Dantanarayana.

On Mon, Sep 3, 2018 at 4:52 PM Pedro Venâncio <pedrongvenancio@gmail.com> wrote:

Hi Vidura,

Just like Moritz said, you need to start by the basics about GRASS.

That said, it is better to create new raster layers than change the existing ones.

To test other wind speed and direction, moisture, etc, just create new rasters with r.mapcalc

https://grass.osgeo.org/grass74/manuals/r.mapcalc.html

Start with constant rasters, using the example in the r.mapcalc manual.

Best regards,
Pedro Venâncio

A seg, 3/09/2018, 06:22, Vidura Dantanarayana <vidurada@gmail.com> escreveu:

Hi Pedro,

Thank you very much for the explanation. That helped me to get a basic idea of what these files do. Then what I did was to change these files. I changed some records in wind speed and wind direction (the files in demomapset/cats). But what I observed was there was no change in the shape of spread even after the alterations. Is there anyone who willing to help me in crating custom files if I provide the relevent information. I need to crate wind, moisture, and fire origin files.

BR,
Vidura Dantanarayana.

On Sat, Sep 1, 2018 at 7:23 PM Pedro Venâncio <pedrongvenancio@gmail.com> wrote:

Hi Vidura,

You need to prepare the input data to r.ros algorithm

https://grass.osgeo.org/grass74/manuals/r.ros.html

The input data needs to be in raster format.

First you need to use the standard NFFL 13 fuel models system (https://www.fs.fed.us/rm/pubs/rmrs_gtr153.pdf) as fuel model input raster.

You also need the fuel moisture content for all sizes and response times (dead 1h, 10h, 100h and live), in percentage.

As Moritz explained to you, you can see that the 1hour_moisture raster of the sample data is composed by:

  • 3% moisture in areas of fuel model 4;
  • 15% moisture in areas of fuel model 8.

You can give homogeneous fuel moisture content for each response times, or different if you have that information, like in the sample data.

Then you need an elevation raster (DEM), calculate slope and aspect (if you don’t have them yet, with r.slope.aspect), and a raster with wind speed (in feet/minute) and another with wind direction (clockwise from north, in degrees).

With this data, you run r.ros and with the output rasters, run r.spread

https://grass.osgeo.org/grass74/manuals/r.spread.html

r.spread just need the an additional raster, with the ignition(s)/starting sources. Pixels of starting sources raster needs to be only values of 1 (ignition points/areas) and 0 (other areas). If you have the ignitions in vector format, just use v.to.rast.

I hope this helps.

Best regards,
Pedro Venâncio

Vidura Dantanarayana <vidurada@gmail.com> escreveu no dia sábado, 1/09/2018 à(s) 14:12:

Hi all,

Thank you very much Moritz Lennert for the explanation and apologize for the mistake I’ve done. I will try what you suggest by myself. Hope It’s okay to questioning again if I found a problem again. Have a wonderful day. Cheers!!!

BR,
Vidura Dantanarayana.

On Sat, Sep 1, 2018 at 2:04 AM Moritz Lennert <mlennert@club.worldonline.be> wrote:

Hi Vidura,

First of all, please keep discussions on the list.

On 31/08/18 09:48, Vidura Dantanarayana wrote:

Hi Moritz,

Really appreciate your help as we are facing this problem for some days
now. First I’m a beginner user. Can you explain what are the categories
and how those used in GRASS GIS?

GRASS GIS is an extremely wonderful and powerful tool, but it does need
some initial learning in order to understand how to use it. Just
answering the questions below will not provide that for you.

I would suggest that you go through some of the basic introductory
material, just in order to get a feeling for GRASS GIS, before attacking
your specific problem.

You could have a look at the following resources (at least for their
introductory parts):

https://grasswiki.osgeo.org/wiki/From_GRASS_GIS_novice_to_power_user_(workshop_at_FOSS4G_Boston_2017)

http://www.training.gismentors.eu/isprs-summer-school-2016/lesson1/grass-gis.html

Or search for “GRASS GIS” in YouTube for some videos.

Let’s say I need to create custom
1hour_moisture (or any other file), so how can I create these files?

How you create these files depends on the data that you have as input.

If you look at the metadata of the file in the demolocation
(right-click->Metadata or ‘r.info 1hour_moisture’ you will this
information at the end:

| Data Description:
|
| generated by r.mapcalc
|
|
|
| Comments:
|
| if(fuel_class==4,3,if(fuel_class==8,15))

This means that the authors had a raster file called ‘fuel_class’ and
used the raster calculator (r.mapcalc) to reclass that file attributing
the value 3 to those pixels who had class=4 in the original map and
value 15 to pixels with class=8.

I have no idea what this original map contained, so cannot help you
further (I don’t know much about fire spread modeling).

Can
you look at the following problem again?

1 categories -----------------------------------------------------> (1)

Map of Fire Origin of Bass River Fire --------------------> (2)

0.00 0.00 0.00 0.00 ---------------------------------------------> (3)
0:no data -----------------------------------------------------------> (4)
1:fire origin ---------------------------------------------------------> (5)

I need to know how to customize the location of origin. I mean, I want
to ignite the fire from another place rather the place specified in demo
data.

If you have the origin location as coordinates, you can create a vector
point at the location using v.in.ascii: in the GUI of that module you
can enter coordinates interactively. Then you convert the map to a
raster map using v.to.rast.

Moritz

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