I am working with Land change modeler in Idrisi taiga. two images are used from 1998 and 2010. When I try to continue I receive this error message: background areas (0) of the two land cover do not match. Please, help me.
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Clark Labs Tech Support Team IDRISI’s Land Change Modeler assumes that cells with the value of 0 are background areas, or areas that are not eligible to undergo any transitions.
When you receive an error stating that the background areas of your two land cover images do not match, it is likely because you have cells with the value of 0 in one image that have a non-zero value in the other image. To test if this is the case, follow these instructions:
- Run the module BREAKOUT on both of your land cover images, selecting to Separate Single Class, and enter 0 as the class you will breakout. This will produce a Boolean image with values of 1 for all cells that have a value of 0 in your land cover image.
- Use OVERLAY to add the two images together. Your output image should contain values of 0 (0+0=0) and 2 (1+1=2) if the background of your two land cover images match. If they do not match, you will have cells with a value of 1 (1+0=1; or 0+1=1). These cells with the value of 1 indicate cells where your background areas do not match in both of your land cover images.
The easiest way to solve this issue is through these steps:
- Use the RECLASS module to reclassify the output image from Step 2 above. Reclassify all values of 1 and 2 to be 0 in the new image (your new background mask) and all values of 0 to be 1 in the new image. This creates a background mask.
- Then use OVERLAY module to multiply your land cover images by the background mask. This will convert all cells that are background in either image to background in both images, and will leave all cells that are not background in either image untouched.
Note that in the new IDRISI, IDRISI Selva, this process has been automated through the use of Harmonize, which automatically checks for and facilitates solving of the following 4 common issues:
- The legends in both maps are the same.
- The categories in both maps are the same and sequential.
- The backgrounds in both maps are the same and have a value of zero.
- The spatial dimensions, including re solution and coordinates, are the same.
David
Clark Labs Tech Support
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Denis Mihailescu Hello, David
I'm using Selva edition and LCM and everything is working fine but I have a question and please tell me if LCM can to that:
-in the later land cover image I have one more class than the earlier one because in the meantime a new crop was grown, so, in the earlier image was wetland and in the later image is rice (in the earlier image there was no rice).
Please tell me if LCM can do that and if, how?
Thank you
Denis
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Denis Mihailescu Well, I think I get it. I harmonized legends by ingesting rice class in the earlier image and now in map changes it's ok. I hope I did it good. Thx
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Clark Labs Hi Denis,
What you did was correct. Even though the pixel count will be zero in time 1 for rice, there will be a transition from wetland to rice for time 2.
Best,
James Toledano
Clark Labs
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Wasswa Hannington iam facing a moreless simillar problem. when i run the idrisi selva LCM it gives me an error that - categories in both images are not the same. but when i check it appears there simillar with same sequence wat can i do. I want to carry out a change analysis, and also predict future scenario. Iam working with wetlands
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INA Error: background area(0) of the two landcover do not match in change analysis step Land change modeler idrisi selva. How to fix it
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Dhea Fenesia Helloo, i have problem too.. i think is the same with this problem.. but when i want to run sub model. The cell size from transision is 1. And in this software said, that if the cell size is must more than 1. How can i do with this problem..
Please help me...
i need your help to my thesis..
thank you before
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