Section with perspective 3D projection

Hi,

I want to do a section view with a perspective background/projection as in this video.

In the video, the change between parallel and perspective doesn’t change the framing - the projection plane stays the same.

When I try to do the same, the perspective camera gets zoomed out really far away from the section and it is impossible to zoom in to the same scale and center point.

When I check the camera positions with F6, I get this:

Default view after clicking on “Set section view to viewport”

Zooming in on the area of interest (in parallel)

Changing parallel to perspective places the camera in the same position as parallel, which means that the frame of the projection plane changes as well.

I managed to manually move the camera approximately to the same position, to get the same frame in perspective, but I can’t match the views 1:1

How did they manage to do it without manually moving the camera in the video?

I see it as an issue of the camera positions. I guess the software would have to know the size of the frame/viewport and re-position the perspective camera after the change, based on its lens length.

PS: After comparing the two frames from the video, I see that the position of the frame isn’t 100% the same. Did they manually position the perspective camera and cut the video? If that’s the case, It’s a bit deceiving…

I managed to recreate the Perspective section viewport with the exact same projection plane as in Parallel, with the help of the Human plugin. To find the exact camera point, I had to manually extract the parallel views projection frame rectangle by referencing camera control points 3 and 4.

image

Is there a way to automatically extract those camera points in grasshopper?

Parallel

Perspective

The main purpose for this effort is to maintain the scale of the “3D” section in the layout. It would be really nice if there was an easier way of achieving this.

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