I have digitized vegetation as polygons covering the canopy of trees in urban areas. Are there any suggestions to check the accuracy of height. I have been manually validating with visual checks, comparing to google earth street view with kmz/kml, though these check are time consuming its the most reliable so far. Please advise if there are easier alternatives.
Google Earth uses SRTM DEM data as source of elevation for most part of the world (see here). DEM is mostly DTM, do not considers any object over the surface. So Google Earth might not be a good source for you. I'd recommend few ideas,
- use high-res elevation data (ie. LiDAR)
- volumetric shadow analysis
- in-situ height information (ie. survey or inventory data)
- high-res SAR Interferometry
In my opinion, a carefully sampled survey data might be a better source of information.