Hello, I'm currently programming things about city generation for a BGE project I have. open street map is a really valuable input for such need, as you know I suppose, since you can retrieve a lot about city geometry worldwide, and generate from it in Blender.
in a recent commit I updated a bit the osm importer to add a better projection from lat/lon to blender units. I think this function, or an equivalent one, should be part of the bpy, maybe in mathutils.geometry, or a more suitable location as you wish : it's really a multi usage function. this could help to bridge with the osm community, and with architects too.. for now the ones I know are a bit reluctant to Blender but I'm hardly working on it, BGE helps a lot actually. the tests I'm doing with lxml xml parser are very conclusive to read write huge osm or extended osm quickly. by extended I mean extra tags about height, uvs,utm coords. a kind of .bosm format I'm writing. anyway here's the proposed function, consider it copyleft. sorry if my proposal does not respect blender guidelines, but I really have no time left :s regards, Jerome / littleneo (from math import radians, sin, cos, tan, sqrt) # given lat and longitude in degrees, returns x and y in UTM (1 KM = 1 BU ) . # accuracy : supposed to be centimeter. community feedback needed. # looks ok so far # http://fr.wikipedia.org/wiki/Projection_UTM # http://fr.wikipedia.org/wiki/WGS_84 # http://earth-info.nga.mil/GandG/publications/tr8350.2/wgs84fin.pdf # http://geodesie.ign.fr/contenu/fichiers/documentation/algorithmes/alg0071.pdf # wiki is your friend (don't ask me about math Im just a writing monkey.) # jerome.le.chat at free.fr def geoToUTM(lon, lat) : # if abs(lat) > 80 : lat = 80 #wrong coords. # UTM zone, longitude origin, then lat lon in radians z = int( (lon + 180) / 6 ) + 1 lon0 = radians(6*z - 183) lat = radians(lat) lon = radians(lon) # CONSTANTS (see refs.) # rayon de la terre à l'équateur a = 6378.137 K0 = 0.9996 # flattening consts f = 0.0033528106647474805 # 1 / 298.257223563 e2 = 0.0066943799901413165 # 2*f - f**2 e4 = 4.481472345240445e-05 # e2**2 e6 = 3.0000678794349315e-07 # e2**3 # lat0. 10000 for South, 0 for North N0 = 10000 if lat < 0 else 0 A = (lon - lon0) * cos(lat) C = (e2 / (1 - e2)) * cos(lat)**2 T = tan(lat)**2 vlat = 1 / sqrt( 1 - e2 * sin(lat)**2 ) slat = (1-(e2/4)-((3*e4)/64)-((5*e6)/256))*lat - (((3*e2)/8)+((3*e4)/32)+((45*e6)/1024))*sin(lat*2) + (((15*e4)/256) + ((45*e6)/1024) )*sin(lat*4) - ((35*e6)/3072)*sin(lat*6) E = 500 + (K0 * a * vlat) * (A + (1-T+C)*((A**3)/6) + (5 - 18 * T + T**2) * ((A**5)/120) ) N = N0 + (K0 * a) * ( slat+vlat*tan(lat)* (A**2/2 + (5-T+9*C+4*C**2) * (A**4/24) + (61-58*T+T**2) * A**6/720) ) return E,N _______________________________________________ Bf-python mailing list [email protected] http://lists.blender.org/mailman/listinfo/bf-python
