Re: [GRASS-user] How to get the area of a polygon in a layer
* Markus Neteler [2018-10-26 22:34:45 +0200]: Hi Nikos, On Tue, Oct 23, 2018 at 5:32 PM Nikos Alexandris wrote: Dear list, is the https://grass.osgeo.org/uploads/grass/sampledata/firedemo_grass7.sh script available. This link is broken. the correct link is: https://grass.osgeo.org/sampledata/firedemo_grass7.sh Where did you find the one you posted? In the main 'Sample data' page, https://grass.osgeo.org/download/sample-data/, I recall. It seems fixed now. Nikos signature.asc Description: PGP signature ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] How to get the area of a polygon in a layer
Hi Nikos, On Tue, Oct 23, 2018 at 5:32 PM Nikos Alexandris wrote: > Dear list, > > is the > https://grass.osgeo.org/uploads/grass/sampledata/firedemo_grass7.sh > script available. This link is broken. the correct link is: https://grass.osgeo.org/sampledata/firedemo_grass7.sh Where did you find the one you posted? Best Markus ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] How to get the area of a polygon in a layer
Dear list, is the https://grass.osgeo.org/uploads/grass/sampledata/firedemo_grass7.sh script available. This link is broken. Thank you, Nikos signature.asc Description: PGP signature ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] How to get the area of a polygon in a layer
Thanks a lot..!!!..Nikos We will look into it If we couldn't do it we will definitely ask your help Thanks again for the help. Best Regards Kalindu Perera On Tue, 16 Oct 2018 at 09:39, Nikos Alexandris wrote: > Kalindu Perera: > > >Commands are as follows > > > >*r.ros,* > >r.ros --overwrite model=fuel_model@demomapset > >moisture_1h=1hour_moisture@demomapset > moisture_live=live_moisture@demomapset > >velocity=wind_speed@demomapset direction=wind_direction@demomapset > >slope=slope@demomapset aspect=aspect@demomapset > >elevation=elevation@demomapset base_ros=my_ros.base max_ros=my_ros.max > >direction_ros=my_ros.maxdir spotting_distance=my_ros.spotdist > > > >*r.spread,* > >r.spread --overwrite base_ros=my_ros.base@demomapset > >max_ros=my_ros.max@demomapset direction_ros=my_ros.maxdir@demomapset > >start=fire_origin@demomapset wind_speed=wind_speed@demomapset > >output=spread_time_observed > > > >*After entering; r.category spread_time_observed,* > >[image: 1.png] > > > >*After entering; r.report spread_time_observed units=c,p,* > >[image: Screenshot from 2018-10-15 21-40-46.png] > > Dear Kalindu, > > thank you for the above. > > If all is right, you might just need to properly prepare the input data > and/or the output of `r.ros`, for example, to label raster categories > appropriately. Then, modules like `r.report` will show also the label > for each raster category. > > When drawing the `spread_time_observed` map, can you identify visually the > raster category of your interest? If yes, pick up the the "Query > raster/vector map(s)" tool (4th button in wxGUI's Map Display window), > and select any pixel of the category of your interest. This will tell > the value (of the pixel you selected) and a label (if any is given). > > Knowing this value, you can extract all pixels of this value using > `r.mapcalc`. For example, say the raster category (or value) of > interest, is 3. Then, something like > ``` > r.mapcalc "category_3 = if(spread_time_observed == 3, 3, null())" > ``` > will create a map with all pixels of value 3. > > I guess using this "category_3" map as an input to `r.surf.area` would > give the area estimation you require. Please, take care to read the > NOTES in `r.surf`area`'s manual about "edge effects" though. > > > Else, I think the easiest/fastest for me would to be to have access to > sample > data (even via a private message). If possible, cutting out (setting via > `g.region`) a small fragment from your study area, and sharing would > allow me to "resolve" this. > > Also, please don't post screenshots (if it is not about part of maps or > other > visuals). For textual output, please always post the output of your > commands > (as in copy and paste) or attach a text file. > > For example, I would copy-and-paste the complete output of (or put in a > text file if a specific output of a command is really too long): > > # in Bash > for MAP in fuel_model 1hour_moisture live_moisture wind_speed > wind_direction slope aspect elevation my_ros.base my_ros.max my_ros.maxdir > my_ros.spotdist fire_origin spread_time_observed ;do r.category $MAP ;done > > # in Windows > see example in: > https://lists.osgeo.org/pipermail/grass-user/2018-June/078526.html > > Nikos > ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] How to get the area of a polygon in a layer
Kalindu Perera: Commands are as follows *r.ros,* r.ros --overwrite model=fuel_model@demomapset moisture_1h=1hour_moisture@demomapset moisture_live=live_moisture@demomapset velocity=wind_speed@demomapset direction=wind_direction@demomapset slope=slope@demomapset aspect=aspect@demomapset elevation=elevation@demomapset base_ros=my_ros.base max_ros=my_ros.max direction_ros=my_ros.maxdir spotting_distance=my_ros.spotdist *r.spread,* r.spread --overwrite base_ros=my_ros.base@demomapset max_ros=my_ros.max@demomapset direction_ros=my_ros.maxdir@demomapset start=fire_origin@demomapset wind_speed=wind_speed@demomapset output=spread_time_observed *After entering; r.category spread_time_observed,* [image: 1.png] *After entering; r.report spread_time_observed units=c,p,* [image: Screenshot from 2018-10-15 21-40-46.png] Dear Kalindu, thank you for the above. If all is right, you might just need to properly prepare the input data and/or the output of `r.ros`, for example, to label raster categories appropriately. Then, modules like `r.report` will show also the label for each raster category. When drawing the `spread_time_observed` map, can you identify visually the raster category of your interest? If yes, pick up the the "Query raster/vector map(s)" tool (4th button in wxGUI's Map Display window), and select any pixel of the category of your interest. This will tell the value (of the pixel you selected) and a label (if any is given). Knowing this value, you can extract all pixels of this value using `r.mapcalc`. For example, say the raster category (or value) of interest, is 3. Then, something like ``` r.mapcalc "category_3 = if(spread_time_observed == 3, 3, null())" ``` will create a map with all pixels of value 3. I guess using this "category_3" map as an input to `r.surf.area` would give the area estimation you require. Please, take care to read the NOTES in `r.surf`area`'s manual about "edge effects" though. Else, I think the easiest/fastest for me would to be to have access to sample data (even via a private message). If possible, cutting out (setting via `g.region`) a small fragment from your study area, and sharing would allow me to "resolve" this. Also, please don't post screenshots (if it is not about part of maps or other visuals). For textual output, please always post the output of your commands (as in copy and paste) or attach a text file. For example, I would copy-and-paste the complete output of (or put in a text file if a specific output of a command is really too long): # in Bash for MAP in fuel_model 1hour_moisture live_moisture wind_speed wind_direction slope aspect elevation my_ros.base my_ros.max my_ros.maxdir my_ros.spotdist fire_origin spread_time_observed ;do r.category $MAP ;done # in Windows see example in: https://lists.osgeo.org/pipermail/grass-user/2018-June/078526.html Nikos signature.asc Description: PGP signature ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] How to get the area of a polygon in a layer
Hi Nikos, Commands are as follows *r.ros,* r.ros --overwrite model=fuel_model@demomapset moisture_1h=1hour_moisture@demomapset moisture_live=live_moisture@demomapset velocity=wind_speed@demomapset direction=wind_direction@demomapset slope=slope@demomapset aspect=aspect@demomapset elevation=elevation@demomapset base_ros=my_ros.base max_ros=my_ros.max direction_ros=my_ros.maxdir spotting_distance=my_ros.spotdist *r.spread,* r.spread --overwrite base_ros=my_ros.base@demomapset max_ros=my_ros.max@demomapset direction_ros=my_ros.maxdir@demomapset start=fire_origin@demomapset wind_speed=wind_speed@demomapset output=spread_time_observed *After entering; r.category spread_time_observed,* [image: 1.png] *After entering; r.report spread_time_observed units=c,p,* [image: Screenshot from 2018-10-15 21-40-46.png] Thank You Best Regards Kalindu Perera On Mon, 15 Oct 2018 at 20:30, Nikos Alexandris wrote: > Please post the exact command you have used (copy-and-paste). > > Then, what does > ``` > r.category spread_time_observed > ``` > > and what does > ``` > r.report spread_time_observed units=c,p > ``` > > return? > > * Kalindu Perera [2018-10-15 16:01:38 +0530]: > > >Dear Nikos, > > > >We have used r.ros and r.spread commands for getting the wildfire > >simulation. > >After that, the output from the r.spread command is spread_time_observed > >layer(This is the output from the simulation) > >We use that layer as the input layer for the r.surf.area command. > > > >We got many area outputs from that command output and couldn't identify > >what area gives the area of the "burned" area > >* I have attached the output from running r.surf.area command as an > >attachment. > > > >** Another question how we can extract only the "burned" area from the > >spread_time_observed layer? > > > >Thanks a lot for the quick reply > >Looking forward to more knowledge > > > >Best Regards > >Kalindu Perera > > > > > >On Mon, 15 Oct 2018 at 15:07, Nikos Alexandris > >wrote: > > > >> * Kalindu Perera [2018-10-15 13:28:15 +0530]: > >> > >> >Dear all, > >> > > >> >We are doing wildfire simulation in Grass GIS. We need to compare the > area > >> >of 2 wildfire spreads after wildfire simulation ran. We tried to > calculate > >> >the area of the spread using r.surf.area module. But we couldn't > identify > >> >which is the area of the simulation from areas given from that. Could > >> >anyone tell us how to get an area from spread like this? > >> > >> Dear Kalindu, > >> > >> please post exact commands you already tried. > >> > >> What are the simulation output maps? > >> Fitst, what does `r.category` and `r.report` return when used for > >> simulation > >> maps? > >> > >> Then, maybe you need to "extract", each time, the "burned" area, then > >> use `r.surf.area` on it? > >> > >> Nikos > >> > >> > >> > > > > -- > Nikos Alexandris | Remote Sensing & Geomatics > GPG Key Fingerprint 6F9D4506F3CA28380974D31A9053534B693C4FB3 > ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] How to get the area of a polygon in a layer
Please post the exact command you have used (copy-and-paste). Then, what does ``` r.category spread_time_observed ``` and what does ``` r.report spread_time_observed units=c,p ``` return? * Kalindu Perera [2018-10-15 16:01:38 +0530]: Dear Nikos, We have used r.ros and r.spread commands for getting the wildfire simulation. After that, the output from the r.spread command is spread_time_observed layer(This is the output from the simulation) We use that layer as the input layer for the r.surf.area command. We got many area outputs from that command output and couldn't identify what area gives the area of the "burned" area * I have attached the output from running r.surf.area command as an attachment. ** Another question how we can extract only the "burned" area from the spread_time_observed layer? Thanks a lot for the quick reply Looking forward to more knowledge Best Regards Kalindu Perera On Mon, 15 Oct 2018 at 15:07, Nikos Alexandris wrote: * Kalindu Perera [2018-10-15 13:28:15 +0530]: >Dear all, > >We are doing wildfire simulation in Grass GIS. We need to compare the area >of 2 wildfire spreads after wildfire simulation ran. We tried to calculate >the area of the spread using r.surf.area module. But we couldn't identify >which is the area of the simulation from areas given from that. Could >anyone tell us how to get an area from spread like this? Dear Kalindu, please post exact commands you already tried. What are the simulation output maps? Fitst, what does `r.category` and `r.report` return when used for simulation maps? Then, maybe you need to "extract", each time, the "burned" area, then use `r.surf.area` on it? Nikos -- Nikos Alexandris | Remote Sensing & Geomatics GPG Key Fingerprint 6F9D4506F3CA28380974D31A9053534B693C4FB3 signature.asc Description: PGP signature ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] How to get the area of a polygon in a layer
Dear Nikos, We have used r.ros and r.spread commands for getting the wildfire simulation. After that, the output from the r.spread command is spread_time_observed layer(This is the output from the simulation) We use that layer as the input layer for the r.surf.area command. We got many area outputs from that command output and couldn't identify what area gives the area of the "burned" area * I have attached the output from running r.surf.area command as an attachment. ** Another question how we can extract only the "burned" area from the spread_time_observed layer? Thanks a lot for the quick reply Looking forward to more knowledge Best Regards Kalindu Perera On Mon, 15 Oct 2018 at 15:07, Nikos Alexandris wrote: > * Kalindu Perera [2018-10-15 13:28:15 +0530]: > > >Dear all, > > > >We are doing wildfire simulation in Grass GIS. We need to compare the area > >of 2 wildfire spreads after wildfire simulation ran. We tried to calculate > >the area of the spread using r.surf.area module. But we couldn't identify > >which is the area of the simulation from areas given from that. Could > >anyone tell us how to get an area from spread like this? > > Dear Kalindu, > > please post exact commands you already tried. > > What are the simulation output maps? > Fitst, what does `r.category` and `r.report` return when used for > simulation > maps? > > Then, maybe you need to "extract", each time, the "burned" area, then > use `r.surf.area` on it? > > Nikos > > > ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] How to get the area of a polygon in a layer
* Kalindu Perera [2018-10-15 13:28:15 +0530]: Dear all, We are doing wildfire simulation in Grass GIS. We need to compare the area of 2 wildfire spreads after wildfire simulation ran. We tried to calculate the area of the spread using r.surf.area module. But we couldn't identify which is the area of the simulation from areas given from that. Could anyone tell us how to get an area from spread like this? Dear Kalindu, please post exact commands you already tried. What are the simulation output maps? Fitst, what does `r.category` and `r.report` return when used for simulation maps? Then, maybe you need to "extract", each time, the "burned" area, then use `r.surf.area` on it? Nikos signature.asc Description: PGP signature ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] How to get the area of a polygon in a layer
Dear all, We are doing wildfire simulation in Grass GIS. We need to compare the area of 2 wildfire spreads after wildfire simulation ran. We tried to calculate the area of the spread using r.surf.area module. But we couldn't identify which is the area of the simulation from areas given from that. Could anyone tell us how to get an area from spread like this? Thank you Best Regards Kalindu Perera ___ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user
