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Re: Data to Device coordinates in Objects [message #54516 is a reply to message #54439]

Tue, 19 June 2007 01:03

Gaurav
Messages: 50
Registered: January 2007

Member

Thanks for the reply Dr. Fanning, you wrote:
> I *really* don't want to get in the middle of this, but
> I presume you "data" coordinate system is some kind of
> map projection set up with the MAP_PROJ_** routines, right?
> So you can go back and forth between 3D and 2D coordinates
> fairly easily. Otherwise, I'm not sure you have a prayer.
> I know I wouldn't.

I don't know about being a better man, but things sure have turned out
in a way that I need to solve this thing.

No, I never used MAP_PROJ*** routines. I simply designed a spherical
'object' that I am trating as the Earth by warping a satellite image
of the Earth on it.

I am able to get the lat/lon of my current cursor position over the
globe by using the PICKDATA routine on the object window by using the
DEVICE COORDINATES as reference. This gives me my position in
RECTANGULAR coordinate system which I convert to spherical coordinates
using CV_COORD routine. Easy as that!

But the trouble is that there is no way to retrace these steps
backwards. I can use CV_COORD to get back to rectangular coordinates
but that only gives me corresponding coordinates for the spherical
model and I simply ahve no way of knowing as to where that pixel is
mapped in the DEVICE SPACE i.e. the DRAW WIDGET that I have used as my
object window. No, COORD_CONV does NOT work- for it is made only to
work in Direct Graphics.

Even a prayer does not appear to work. Help!

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[Message index]

		Data to Device coordinates in Objects By: Gaurav on Mon, 18 June 2007 03:13
		Re: Data to Device coordinates in Objects By: Gaurav on Tue, 19 June 2007 01:03
		Re: Data to Device coordinates in Objects By: David Fanning on Mon, 18 June 2007 08:19

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