oh I meant no time for the proposal process, if you agree for sure I can push a geospatial_utils.py module with geo_to_utm() in it.
such module would need a real mathematician to improve and to address common geospatial needs, if its only me it will turn into a 2 functions module I won't be able to explain exactly ;) Jerome Le 10/09/2012 02:14, Campbell Barton a écrit : > Hi jerome, such functionality is indeed handy, but think it belongs in > its own module, > perhaps "bpy_extras.geospatial_utils" > > ./release/scripts/modules/bpy_extras/geospatial_utils.py > > Also, wouldn't it make sense to have a function to do the reverse conversion?, > geo_to_utm() / utm_to_geo() > > If you don't have time to do this, its fine, but could add in a > comment that its a TODO. > > On Mon, Sep 10, 2012 at 7:16 AM, jerome <[email protected]> wrote: >> 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 > > _______________________________________________ Bf-python mailing list [email protected] http://lists.blender.org/mailman/listinfo/bf-python
