Vacant land inventory

Working on a large 4 county area around Houston, TX. Wanted a single image to analyze parcel data to do a vacant land analysis.  This is a test to mosaic the 4 county individual NAIP images into a single ECW image.  I told this program to make the NoData areas transparent...not sure how this will turn out.

More to come...
The resulting imagery of the 4 county mosaic is about 4.3gigabytes compressed and would be about 120gigabytes uncompressed.  The lime green are unimproved parcels clipped out any areas within the 100 year floodplain.  This is a rough quick analysis done using only vector data from the appraisal districts and the associated attribute data.  An image classification analysis would help weed out false results from bad attribute data.

I had to go through these results and do a lot of manual removal.  State/County/School/Hospital/Cemetery parcels and for some reason airports, don't have declared improvement values in the CAD data.  This results in many false positives for "vacant land".