comp.lang.idl-pvwave archive: archive » Question about projection for Google Earth

Home » Public Forums » archive » Question about projection for Google Earth

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: Question about projection for Google Earth [message #85577 is a reply to message #85576]

Mon, 19 August 2013 00:27

Fabzi
Messages: 305
Registered: July 2010

Senior Member

On 08/19/2013 07:04 AM, timothyja123@gmail.com wrote:
> "The problem is that my lon/lat values contain a different number of values and
>Map_Proj_Forward() is complaining about this. Whay do they need to be
the same?
>My overlay is a rectangular shape rather than a square why can this
not be handled?"

I don't really understand what you mean with "rather than a square" but
Map_Proj_Forward() converts point coordinates into other points
coordinates. As far as I know, points always have (at least) two
coordinates so if you want to transform N points you should have N lats,
and N lons. The real question is: why do you have a different number of
lat and lon values?

The most typical case would be that your data is in equirectangular
projection. For example:
IDL> nx = 360
IDL> ny = 180
IDL> lon = FINDGEN(nx) - 179.5
IDL> lat = FINDGEN(ny) - 89.5

if you want to pass them to map_proj you need "rectangles" as you say:
IDL> lon = lon # (LONARR(ny) + 1)
IDL> lat = lat ## (LONARR(nx) + 1)
IDL> help, lon, lat
LON FLOAT = Array[360, 180]
LAT FLOAT = Array[360, 180]

not sure if that helps but I am quite sure that Map_Proj_Forward() is
not going to accept different vectors of lat/lon in the close future.

Cheers

Report message to a moderator

[Message index]

		Question about projection for Google Earth By: timothyja123 on Thu, 08 August 2013 19:11
		Re: Question about projection for Google Earth By: David Fanning on Thu, 08 August 2013 19:26
		Re: Question about projection for Google Earth By: timothyja123 on Thu, 08 August 2013 21:50
		Re: Question about projection for Google Earth By: David Fanning on Fri, 09 August 2013 03:51
		Re: Question about projection for Google Earth By: timothyja123 on Sun, 18 August 2013 22:04
		Re: Question about projection for Google Earth By: Fabzi on Mon, 19 August 2013 00:27
		Re: Question about projection for Google Earth By: David Fanning on Mon, 19 August 2013 05:26
		Re: Question about projection for Google Earth By: timothyja123 on Sun, 01 September 2013 22:15
		Re: Question about projection for Google Earth By: David Fanning on Tue, 03 September 2013 06:03

Previous Topic:	Keyword UNAME not allowed in call to: CW_FSLIDER
Next Topic:	parallel sign in postscript output in device fonts (direct graphics)

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Wed Oct 08 19:28:25 PDT 2025

Total time taken to generate the page: 0.00426 seconds