# Lessen degree of perspective in 3D grid (reduce convergence)

Please see the following image:

Which mathematical method or POV-Ray/OpenGL command will lessen the convergence of a grid like this? (The grid converges too quickly; **theta should be 90 degrees**, matching the center line, for this purpose.)

Perspective is still desired, but convergence should happen at a slower rate, as if the distance was shorter or you were using a telephoto lens.

Although this image is from Blender, the methods being used are OpenGL and POV-Ray so a solution in either method would be appreciated.

I have some lines modeled in OpenGL and POV-Ray.

I have tried *location*, *look--at*, *angle*, *right* and *up* in POV-Ray, including camera transformations like *rotate*, *scale*, *translate* and *matrix*.

In OpenGL I have tried *gluPerspective*, *glFrustum* and *glDepthRange*.

Does anyone have a solution to this problem?

(Also, looking down on the grid is not an option in this case)

## Answers

You're after an orthographic projection...

glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(left, right, bottom, top, near, far); glMatrixMode(GL_MODELVIEW);

It's always nice to be able to swap between orthographic and perspective though since moving around a scene in orthographic can take a while to get used to.

There's an image here... http://blender.stackexchange.com/questions/648/what-are-the-differences-between-orthographic-and-perspective-views

**edit**

To keep using perspective, but with less perspective effect, you can decrease the field of view parameter. Unfortunately this will make the projection appear to zoom in. To undo the zoom, move the camera back. You can then update the near/far accordingly if need be.