[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

*Subject*: Re: Polar to spherical coordinates*From*: Patrick Ford <pford(at)bcm.tmc.edu>*Date*: Thu, 27 Apr 2000 21:30:14 -0500*Newsgroups*: comp.lang.idl-pvwave*Organization*: Giganews.Com - Premium News Outsourcing*References*: <8e1rpu$k36@gazette.bcm.tmc.edu> <MPG.136e22dd5bfafe0c989aeb@news.frii.com>*User-Agent*: YA-NewsWatcher/4.2.5*Xref*: news.doit.wisc.edu comp.lang.idl-pvwave:19433

Oh, if what I wanted was that easy. What I would like is more akin to the MAP_IMAGE function. I want to convert a 2D array "image" into a 3D array "image" such as a polar projection to a sphere ( 3D array) and back again. Using the WHERE function and the CV-COORD function I have partially done what I need to do. It looks like I will need to create a look-up-table (LUT) to translate the coordinates. It still seems like there must be a trivial solution other than to create a LUT and its inverse. I vaguely recall from some math-sci course I took in college 20 or so years ago that we used transform to "transform" from one domain to another. This is what I am looking for, a function that will do this transform. If I make one, I will post it so that it will be decreased in size by 80% and speed by 300% as usual since I still think in FORTRAN or C and not IDL. Thanks In article <MPG.136e22dd5bfafe0c989aeb@news.frii.com>, David Fanning <davidf@dfanning.com> wrote: > Patrick V. Ford (pford@bcm.tmc.edu) writes: > > > I have a problem that is screaming at me that there must be a simpler > > solution in IDL than I have devised. I am attempting to relearn IDL, > > after months of being away from it, and the math after decades from it and > > I have not found a built-in procedure that does the trick. > > > > The problem in its, simplest form, is that I want to take a 2-D polar > > plot and transform it into a 3-D hemisphere and vice versa. More > > accurately, a polar plot to a 3-D hemi-ellipsoid with varying axes and > > thickness, i.e. more than just a surface plot. The manner that I am > > thinking how to do this is to sample the polar plot along its radius and > > map it to the hemisphere(with for loops). It seems to me that this is > > likely common in IDL to map from polar to spherical coordinates and to > > warp shapes. Since I don't wish to reinvent the wheel, and not a good > > wheel at that, I would appreciate being pointed in the right direction. > > I'd start by trying to use CV_COORD to map from polar to > spherical coordinates. > > Cheers, > > David

- Prev by Date:
**Re: linking programs/ procedures** - Next by Date:
**Interploation/extrapolation problem** - Prev by thread:
**Re: draw window mouse events** - Next by thread:
**Interploation/extrapolation problem** - Index(es):