Hi Vijaya,

If you're using ARCGIS, my suggestion would be to run a supervised classification over your images, then convert the classification raster to a polygon format (Can be found in - Arc toolbox - Conversion Tools - From Raster - Raster to Polygon).

From here, you should be able to calculate statistics in your attribute table, which should give you the areas for each class in the image.

If you repeat the steps for each multi-temporal image, you should be able to measure the change in area.

I hope this helps, if not, let me know.

Best wishes,

Aneurin

If you have  ENVI software, you can easily calculate it using post classification change analysis.

Thank you Aneurin for valuable suggestion. Now my doubt is I have only two multitemporal images with respect to same geological area with different period. Which method i have to adapt to get change detection then how i have to measure area of changed image.

Thank you Abdullah sir, yes I have ENVI software. do you have any procedure to do post classification oriented change detection and to measure area in Km^2. Please can you elaborate the work still more sir. 

Hi, sir

Is it possible to do area measurement for change detection using SAR images and is it possible to measure in km2.

Hi Vijaya,

If you've run the process in ARCGIS that I mentioned above, there are a couple more steps I forgot to add on my previous response.

Firstly, you'll need to add a field to the attribute table (I'll refer to it as 'area').

Secondly, you need to turn on the 'Editor' toolbar, right click on the 'Area' column, select the 'Calculate Geometry' tool. When this window opens, you'll need to ensure the 'Area' column is selected. You can also set the units to km2. Then it's a case of running the process.

Finally, if you sort the attribute table by class, you can highlight all the polygons and calculate the area it covers.

As far as I'm aware, this would need to be repeated on both images individually, and then the change in area calculated in Excel.

I hope this answers your question, let me know if I haven't.

Best wishes,

Aneurin.

Thank you Aneurin, I have understood the procedure clearly,

which is possible for SAR images because SAR is microwave sensor images, but this area measurements are possible only to do Raster on visible band  of optical images. Is it know!

Can you please give some idea to proceed with only SAR images. which type of SAR images i have to use if i need to satisfy my objective.