| Re: Display and Navigate Image in IDL 8.2 [message #81435 is a reply to message #81350] |
Thu, 13 September 2012 07:23   |
lecacheux.alain
Messages: 325
Registered: January 2008
|
Senior Member |
|
|
Le jeudi 13 septembre 2012 15:15:14 UTC+2, David Fanning a écrit :
> alx writes:
>
>
>
>> For those who might be interested, my equation:
>
>> res = ((m.a + 135)*2*!dpi)/256/2^zoom
>
>
>
> 135!? You are going to have to explain that. :-)
>
>
>
> Cheers,
>
>
>
> David
>
>
>
>
>
>
>
> --
>
> David Fanning, Ph.D.
>
> Fanning Software Consulting, Inc.
>
> Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
>
> Sepore ma de ni thui. ("Perhaps thou speakest truth.")
My previous message should have been supressed and not published !
Anyhow, what I intended to propose is the formula :
res = ((m.a + altitude)*2*!dpi)/256/2^zoom
in which 'altitude' is the altitude difference between the geoid and the ellipsoid at the center of the map. This would makes sense. Unfortunately, since its value is not equal to the 'true' altitude (that counted above sea level and which is usually well known: 135m in the particular example I was checking!), this cannot help us much.
There is no other way, I guess, than additionnaly using relevant geoid reference data.
Sorry for the parasitic post...
alx.
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
