How to project a 3D wave to an orthographic map

Share icon

Hello,

I have a 3D wave (1x73x144) and two 1D waves: one for latitude (n=73) and one for longitude (n=144). Before appending this 3D wave to an orthographic map, I need to project the data (currently in degrees) into an orthographic projection. However, I am unsure how to correctly transform these waves for the projection.

Could someone kindly guide me on how to accomplish this?

Thanks in advance!

Jack

We would normally call a 1x73x144 dataset a 2D wave; there's no real difference between a 1 layer 3D wave and just a bare ("no layer") 2D wave.

You want the Project operation.

Igor ships with a Map Projections Demo experiment in File->Examples->Feature Demos 2->Map Projections Demo.

You might also want to look at ImageTransform's Warp method.

December 21, 2024 at 03:32 pm - Permalink

Hello Jack,

I am guessing that your (73,144) values are coordinates at which your "3D" wave provides scalar values.  You can use the Project operation (which works in degrees) to convert to one of the supported projections.  Once you obtain the projection, you apply the scalar value from your "3D" wave to the new points.

The project operation assumes that you are working with data on a sphere and since you are asking about orthographic projection I can't avoid thinking that you could simply express your data as a parametric surface ( a (73,144,3) wave) where you use XYZ values for a sphere of radius 1 and express the 73x144 points using standard spherical coordinates.  Once you have the parametric surface you can display it in Gizmo and apply the scalar data as a color map.  A similar example is provided in File Menu->Example Experiments->Visualization->GizmoSphere. 

HTH,

AG

January 6, 2025 at 03:56 pm - Permalink