Hello, Just a little note from a guy who seems to have nothing better to do (but should).
I was working with resolutions and scales and tilecache and I was trying to adjust everything to have a set of predefined levels corresponding to fixed scales (1 : 1M, 1 : 500 K, ...). I seems that in fact it's better to works with resolutions instead of scales when using tilecache and that the base extend should correspond to 2x2 tiles at the max resolution. I have a TIFF file in 3200 meters per pixel, I've had to adjust my EXTEND so that it correspond to 3200*512 to avoid rounding problems and missing tiles. Now, the scale controller show a scale based on the following calculus : 3200 pixels/meter * 72 ppi * 39.3701 inch/m --> 1 : 9 M The 72 ppi and 39.3701 inch/m values are defined in the Utils.js 72 ppi is the same value used by Mapserver by default. I've made a some research on Internet to understand how it works and maybe we should add a little note on the OpenLayer site. All this to say that if I understand well, we should rename the variable "DOTS_PER_INCH" of the Utils.js file into "PIXEL_PER_INCH" to be more correct (I know, I should have done more important things this morning ^^) . http://www.scantips.com/no72dpi.html http://en.wikipedia.org/wiki/Pixels_per_inch http://en.wikipedia.org/wiki/Dots_per_inch Tchule. _________________________________________________________________ http://imagine-windowslive.com/hotmail/?locale=en-us&ocid=TXT_TAGHM_migration_HM_mini_2G_0507 _______________________________________________ Users mailing list [email protected] http://openlayers.org/mailman/listinfo/users
