PDA

View Full Version : Shift Cam - compensate pitch?



SaT
11-12-2013, 03:10 AM
In LightWave 11.6, I notice that there is a new option for the Shift Cam: Compensate Pitch?
Can someone please explain me that option. I can see that the image is slightly zoomed in when activating this but when would you want to use it?

spherical
11-12-2013, 05:51 PM
Shift Cameras are usually view cameras, where you can pitch and yaw the lens and film plane in order to correct perspective and change the depth of field plane. Most often, this technique is used in architectural photography to bring the verticals back into being parallel when shooting at an up or down angle.

jameswillmott
11-12-2013, 07:03 PM
Imagine you are looking at the side of a building. As you pitch up with the shift cam you are keeping the face you are looking at flat to the screen, but the point you are looking at is higher and higher up the building, and therefore further away. Since it's further away the size of the building in the frame is going to shrink. Compensate Pitch scales the image so it stays the same size all the time, and was also needed for compatibility reasons.

SaT
11-13-2013, 02:14 AM
Thanks to both of you. Well I know what a shift cam is, because I use it almost every time. It was just about the 'Compensate Pitch'.
It is funny that this type of cam works a little bit different in every new LightWave version.

spherical
11-13-2013, 07:18 PM
Well, that's what I get for not actually opening Layout and answering from memory. I thought you were referring to the setting that actually is labelled: "Use Cam Pitch". Not finding anything about Pitch Compensation in ANY manual back through v10 (why am I not surprised?), I played with the Shift Camera and it appears to be applying the distortion center at the level of the camera above/below origin; not at the center of the frame. At a low pitch angle, the effect isn't as pronounced as it is when you raise the camera and apply a 36-45 degree pitch. Doing so then alters the field of view dramatically, such that the entire object is no longer contained within the frame. All of the distortion is being applied below the camera elevation, instead of "rotating" the frame at the center. Way up there, with Pitch Compensation on, the camera just zooms; without changing the perspective—resulting in an unusable POV. Lower down, the perspective correction does happen between PC on/off.

SaT
11-14-2013, 01:50 AM
Thanks. You are right. When using a 45 degree pitch the effect becomes quite clear. When using the Pitch Compensation the object is zoomed so that the visual distance is always kept the same.

lertola2
11-14-2013, 01:07 PM
Imagine you are looking at the side of a building. As you pitch up with the shift cam you are keeping the face you are looking at flat to the screen, but the point you are looking at is higher and higher up the building, and therefore further away. Since it's further away the size of the building in the frame is going to shrink. Compensate Pitch scales the image so it stays the same size all the time, and was also needed for compatibility reasons.

That is very interesting and it gives me an idea for a new feature that might be very handy. If you draw a limited region in the perspective window that should correspond to some combination of shift camera settings. So when working with limited region you could have the option to create a new shift camera that has the exact image as the limited region. That would useful for examining a small region of your image.

spherical
11-14-2013, 07:58 PM
OK, I've read this five times and it doesn't make complete sense to me. One of us isn't grokking the function of a shift camera. Perhaps you mean Advanced Camera?

lertola2
11-15-2013, 03:06 PM
OK, I've read this five times and it doesn't make complete sense to me. One of us isn't grokking the function of a shift camera. Perhaps you mean Advanced Camera?

I just meant that I think there exists some shift camera settings that will reproduce the view seen through the limited region in the perspective camera. If that is true then it should be possible to have a new command that would create that shift camera.