Variables such as distance to roads/streams/urban are commonly used for land change prediction in LCM. Other social and economic data such as population and investment are also important for land use change. How to add them into LCM through the Transition Sub-Model Structure panel?

Thank you so much!

-Jun

• Siewe Siewe

I do not even have a clue on how to create a variable like distance to roads and streams from my road and stream layer. I will appreciate any and all help in doing this. I will also like to include my population data  like Jun, if anyone has a clue. Thank you in advance,

• FlorS

Hi,

Developing explanatory variables in Idrisi is easy and there are lots of modules that you could use, depending on the type of variable you want to develop.

In order to calculate distance based variables like distance to roads, distance to markets, distance to populated places, or rivers, you need first to have the features you want to calculate distances from as Boolean images. Then just use the DISTANCE module for Euclidean distances or the COST distance module to get cost distances. Cost distances are better than Euclidean distances as they are based on frictions. Two areas can be close spatially (small Euclidean distance) but if the area is not accessible e.g. there are no roads connecting, they will have high cost distances. Regarding population density and other socioeconomic variables that may be available from census information, the module DISAGGREGATE redistributes the values based on a specified pattern.

One important thing to consider is that variables need to have the same projection, rows, columns and extent of the land cover images. so you should check this before including them into the model.

Flor

• Siewe Siewe

Thanks Flor. I do have another question if you do not mind. What tool in IDRISI can I use to make sure that the rows and columns of two images match each other? Thanks in advance for your help. Siewe3

• JUN ZHOU

Siewe, as for your question about matching two image, what I did is unifying the extent, cell size and projection system in Arcgis. The easiest way might be change the "Environment" where you can set the cell size, extent and projection system. Then use tool such as "raster calculator" (not for new calculation, but only to export a new layer with the newly set up "Environment") and the exported layer "=" the old one. Do the same for all images and you will have unified images with the same extent and cellsize and therefore unified rows and columns .

• Siewe Siewe

Thank JUN ZHOU for your reply. I have an idea of what you are explaining, but I got a little confused with your use of "Environment". I will be glad if you can explain just a little further. In what "environment" in ArcGIS can I set the extent, cell size and projection at the same time. Thanks again for your speedy reply. Siewe3

• JUN ZHOU

"Environment"

For example, when you open the tool "Raster Calculator" or any other tool from the toolbox list, you will see a button called "Environment" in the open window.

• FlorS

Hi!  There is no need to go to Arc to do this!!

Here is my response to a previous post on the same issue:

In IDRISI, you can harmonize the spatial characteristics of your data using the module PROJECT (even if you have them in the same projection) In PROJECT select as input the image that you want to modify. Specify the output name and the output projection (if you need to change only rows and cols, then specify the same projection of your input data) Then go to "output reference information" here you can copy the rows and col and extent parameters from the file that has the correct extent or enter them manually. Run it and the output should have the same extent, rows and cold of the image you copied the parameters from. NEVER change the parameters from the metadata because- although the software will not complain -  the output will be garbage as you will be modifying the structure of the raster file.

• Atalel Getu

Hi Flors, I have a river and slope raster data created by a clipping my study area. i tried to put as a driver variable in LCM, but it says that the dimension of these drivers is don't much with the earlier landcover maps. The road raster that I created with the same procedure works with the same dimension as landcover maps.

So, do you know why the dimension vary in this case?

Is it possible to correct the dimensions (rows and columns) to make the same as  landcover classes?. If possible, could you explain me please? Do you think it doesn't have a problem in the out put ?

thank in advance considering my problems!!!

• FlorS

Hi Atatel,

Are you doing this in Arc or Idrisi? I recommend using the approach described above (in my answer of Sep 3rd), as all the images need to have the same extent, rows and columns. Just use your land cover map in the "copy parameters from" box within "output reference information" .

Flor

• Anna

pls help me how to prepare population density as factor input in idrsi ???

• EG Dy

Hello, everyone. I too have a concern.

I would like to include commodity prices (ex. livestock and cotton) in the model. How do I go about generating the driver? Do I have to consider the physical aspect of the area i.e. slope or elevation? Or do I simply distribute the prices to the districts (the study area is a whole region with 8 districts) and directly input it to the model? I would appreciate if someone can explain this a little further.

As to the data type, commodity price is a categorical data. Should I convert this to a continuous data? If so, what module should I use?