Apart from NDBI, could you name a few indices for urban expansion? I have done some search on google but haven't found anything that could help me. Perhaps,
What I'm interested is also: road/infrastructure, parks, parking lots, commercial areas development in the urban environment.
Edit:
I need to analyze some orthophotos of a city and to do that I need to apply some indices to my analysis. As for software, I'm going to have at my disposal: ERDAS, ArcGIS, Open Source.
I assume then you are working with the Red, Green, Blue and nIR bands if you have orthophotos. I would start investigating land cover classification using supervised maximum likelihood classification (MLC). Both ArcGIS and Erdas have a variety of tools for image classification, including MLC. If needed, you can include indices as essentially another "band", which allows for more information during the classification. You can add the index to the raster stack in ArcGIS using Composite Bands or in Erdas using the Raster Stack tool.
If you have only 4 spectral bands (R,G,B,nIR), you are fairly limited in the variety of indices available to you. However, I would recommend using NDVI as additional information for your land cover classification. This index is typically used to assess vegetation, although it can also be used to provide information about where vegetation is absent, as would be the case for urban or developed areas.
