Converting lat/long distance to miles.

[Lowell Filak]

The following message was sent by Camden Daily <cdaily at GMAIL.COM> on
Wed, 26 Jan 2005 16:15:38 -0600.

> Ok.  I had axed all my projection blocks because I'd converted all my
> shapefiles to lat/long (epsg:4326) using ogr2ogr, so I figured I
> didn't need them.  Should I still add a projection block to the map
> and each layer?
>
> My map file has a 'units' set to dd, since that is how I set my
> extents (and I need to set them that way, since I'm centering off a
> given lat/long point in mapscript).
>
> Could I set the extents in mapscript using dd, and then change the
> units to miles for my distance calculations?

Camden,

I don't think it is possible to just change the units to miles for a DD
projection, but I've never tried that.? However, being that all your
layers and map are epsg:4326, temporarily assigning another epsg code to
the map and units to miles with each layer staying epsg:4326 shouldn't
be to difficult.

Lowell