[GRASS-user] Understanding Raster Map Input Files

[Pedro Venâncio]

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 at 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 at 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://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
>>
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