| 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869 |
- From: Glynn Clements <glynn*gclements.plus.com>
- Date: Mon, 18 Dec 2006 17:28:43 +0000
- List-Archive: <http://grass.itc.it/pipermail/grass-dev>
- The relevant files (all installed into $GISBASE/etc) are:
- 1. parms.table
- One line for each known projection. A sample entry:
- AEA:Albers Equal Area:LAT0=ask,23.0;LAT1=ask,29.5;LAT2=ask,45.5;LON0=ask,-96.0;X0=ask,0.0;Y0=ask,0.0
- The first field is the projection name, as used by the old geo.h file.
- AFAICT, the corresponding +proj= parameter is identical except in
- lower case.
- The remainder of the line (after the colon) is a semicolon-separated
- list of parameter definitions of the form parm=spec. The LHS is the
- parameter name as used by geo.h; these don't necessarily match the
- corresponding the proj parameter, but you can translate them using the
- desc.table file (see below).
- The RHS has two parts, separated by a comma. The first part is either
- "ask" or "noask", corresponding to whether or not g.setproj should
- prompt the user for a value. The second part is either "nodfl" or a
- default value. Note that the combination "noask,nodfl" never occurs;
- if an option is marked as "noask", there will always be a default
- value.
- 2. desc.table
- One line for each known parameter (other than +proj=). A sample entry:
- LON0:lon:lon_0:Central Meridian
- The first field is the parameter name as used by the old geo.h file,
- and as used in parms.table.
- The second field is the type, and can be one of:
- bool int float lat lon zone
- This determines the set of valid options for the parameter (the "zone"
- type corresponds to the UTM zone).
- The third field is the name of the corresponding proj parameter
- (without the leading "+"), and is the key stored in the PROJ_INFO
- file.
- The fourth field is a textual description of the parameter.
- 3. units.table
- One line for each known distance unit. A sample entry:
- feet:foot:0.3048
- The three fields are (in case it isn't obvious) the plural form of the
- name, the singular form, and the size of the unit in metres.
- However, note that g.setproj still has a fair number of special-case
- hacks. Some of those are useful-but-not-essential (e.g. automatically
- selecting the correct ellipsoid for certain projections), while others
- are necessary (e.g. the zone= and south parameters for UTM need to go
- into the WIND/DEFAULT_WIND files as well as the PROJ_INFO file).
|
