| Re: pixmap drawables in Object Graphics? [message #28564 is a reply to message #28560] |
Tue, 18 December 2001 08:05   |
karl_schultz
Messages: 13
Registered: August 2001
|
Junior Member |
|
|
"Martin Downing" <martin.downing@ntlworld.com> wrote in message news:<82wT7.22741$4e3.3004657@news6-win.server.ntlworld.com>...
> Hi all,
>
> This is similar to previous queries on object graphics and pixmaps but I
> would appreciate running this by the experts.
> I am writing a program to fit projections of a 3d surface model to its
> silhouette in an image (e.g. a radiograph). This method allows an estimate
> of object position to be recovered from the knowledge of the object shape
> and the image. My 3d data is a triangulated mesh which can be best stored as
> a IDLgrPolygon object. This is attractive as you can then easily specify a
> graphics model to render the object at specific rotations, and projections
> of complicated polygon objects can then be drawn rapidly using OpenGL.
> However, as this is part of a fitting process, I then read the drawable back
> into an image buffer using say tvrd(), do some image processing to get a
> goodness of fit quantity and repeat until a sufficient fit is found. I do
> not need to see each projection in an exposed draw widget, but as far as I
> can gather, pixmaps are not implemented in object graphics. So as I see it,
> my only option using object graphics is to use normal draw widgets, which
> seems like overkill. Is this true and does anyone else have a better idea.?
It sounds like you want to do off-screen rendering and then perform
image analysis on the result. Use IDLgrBuffer as the destination
graphics object (instead of an IDLgrWindow). Fish the pixels back out
with the IDLgrBuffer::Read method, which puts the pixels in an
IDLgrImage object. You can then get the pixels out of the IDLgrImage
object for analysis. All this can happen without drawing anything to
the screen.
Something like:
oBuffer = obj_new('IDLgrBuffer')
oBuffer->Draw, oView
oImage = oBuffer->Read()
oImage->GetProperty, DATA=imageData
What happens under the covers is that IDL renders your scene into a
completely device-independent off-screen frame buffer, using a
software renderer.
Karl
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
