> I'm working with a system that draws a map from certain information. > Lambert's projection seems to suit well to our needs.
... > I found a formula explaining the projection at > http://mathworld.wolfram.com/LambertConformalConicProjection.html . > Unfortunately there is no explanation that what units x and y are, so > drawing them or further conversion is impossible. x and y are the Cartesian coordinates on the projected map. To be useful, they generally need to be scaled, translated, and rotated to the particular dimensions of the map you wish to output. I have a small library of classes which implement albers conical equal are, lambert azimuthal equal area, and lambert conformal conic projections here: http://mike.teczno.com/map-code.tar Those files are the beginnings of something I am planning to contribute to the PEAR project, so if anyone has feedback or other projects they wish to see added, they are very welcome. See the test/lambert_conformal_conic.php file for an example of usage and a brief unit test. Note that the reference latitude & longitude and the standard parallels described in the mathworld write-up are the four arguments to the constructor, and that all lat/long units are expected in radian, not degrees. Sorry that the comments aren't as extensive as they ought to be. --------------------------------------------------------------------- michal migurski- contact info and pgp key: sf/ca http://mike.teczno.com/contact.html -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
