Wednesday, November 30, 2011

VectorWorks Mapping Satellite Images on Site Model workflow

The following is a workflow to georeference satellite images (available from NearMap) and map the image onto a 3D Digital Terrain Model created by the CAD program VectorWorks. 

CAD Program [Vectorworks]: 
1. Create a new site file and nominate the Origin at a given Easting and Northing (to 100M intersection) such that site sits central to a 200M x 200M square. 
2. Draw 200M x 200M 3D polygon (Z=0) with bottom LH corner coincident with Origin. 
3. Create a 'Site Model' with a 200M x 200M Site Boarder with bottom LH corner coincident with drawing Origin. 

Geoscience Australia:
4. Determine Latitude, Longitude and Grid Convergence for the Easting and Northing in 1. above.

Vectorworks: 
5. Export 3D polygon in 2. above to .kml file with Lat, Long., and Grid Convergence as per 4. above. 

NearMap Hypertiles: 
6. Import .kml file [ensure polygon is aligned to true North]. 
7. Save tiles [use max. tile size available - file size should be <4MB].

Vectorworks: 
8. Create new texture by importing .jpg created in 7. Set size to 200,000 (200M). 
9. Apply texture to Site Model. 

The satellite image should be georeferenced precisely with the DTM.