I want to make transmapped plane billboards that should always face the camera.  I've just spent the last half hour googling for some solution to this problem.  I think the Dr. did a tutorial on this, but I''ve never been able to find it.  I know there were some X-Frog trees in the marketplace that did this, but it seems like I should be able to do this without buying a product. 

I've tried using point at, but while the prop did point at the camera, it also wanted to rotate when the camera moved.

That's the nature of having it "face the camera", a plane billboard will have to rotate to follow camera motion.

you mean they always hafta be normal to the line-of-sight of said camera?
assuming said camera is fixed in space and only rotates?
that would mean they are always in centre-frame IMVHO.

Point-at works better with the dolly camera.  

You can position a non visible prop and point-at it . If the camera doesnt move too much or in the wrong direction  it works ok.  Its a limitation of billboard type props.

I know it has to rotate along the Y axis in order to remain parallel the camera.  When I tried using "point at", the plane rolled like a wheel as the camera panned over it, though it did remain parallel to it.  (IIRC, setting limits on rotation had no effect due to the pointing at the camera.) 

I once tried a free weather prop that simulated rain fall in front of the camera.  It always remained parallel to the view plane, but seemed to be parented to the camera.  I want a plane that is always parallel to a chosen camera but stays fixed in its scene location even when that camera moves.

Quote - you mean they always hafta be normal to the line-of-sight of said camera?
assuming said camera is fixed in space and only rotates?
that would mean they are always in centre-frame IMVHO.

Billboard objects are common, especially in games.  They face (are normal aligned to) the camera no matter where it is.  They don't have to be in the centre of the frame, as their orientation should change dynamically as the camera moves.  When animated, it can be very easy to spot them, especially if the camera's elevation changes.  I fully understand the practical limits of billboards, but not how others have successfully managed to create them for use within Poser.

You need to use a dummy helper to hold your Billboard in place.  Use a prop primitive, and place it exactly where you want your Billboard to pivot on the Y axis.  Then parent the Billboard to the prop primitive.  Then set your billboard to point at the camera.  Then when you rotate the camera, the Billboard will rotate on its axis, but remain anchored in place.
DPH
PS: be sure to remember to uncheck Visible on the dummy helper's/prop primitive's property tab.

 Isn't this also a question of where the center of Origin of the billboard is? It should rotate around its Origin if I understand the problem correctly. In that case it wouldn't be necessary to use an exstra prop.

Hm. This calls for some experiments... I tried to make my Ghosts face the camera but couldn't make it work. So perhaps the Center of Origin isn't enough in itself... I'll have to see what happens if you add an extra prop... 

The moment that you parent something to a dummy helper/primitive prop, then that dummy helper becomes the center of origin of you object-character.
DPH

When I originally tried this I was getting rotation on two axes, not just the one I wanted.  Has anyone else had that happen?    The object did rotate around its center of origin, but on two axes, not just the one (It maintained it's orientation to the camera but rolled like a wheel as the camer panned acroos it). 

(Assuming the camera is just moving laterally, the object should pivot around its Y axis.  Moving the camera up and down would naturally rotate the object around a second axis.  This is not what I was getting.) 

I'll try using a dummy, but I'm not sure which object needs to point at the camera with that method.

point at uses both the item center (green +) and the red +  from joint editor to align the prop with the point at target. You might check where those two are in relation to the camera. A prop parented to the camera may allow you to get the poit at target in a position to pivot the billboard. 

Another option might be to turn on limits and set limits to 0 max and min for the rotationss that tilt the prop.

The Billboard is pointed at the camera as before.  The dummy remains stationary, and anchors the billboard to the spot.  The dummy's job is simply to act as the axle on which the billboard rotates.
DPH

Quote - The Billboard is pointed at the camera as before.  The dummy remains stationary, and anchors the billboard to the spot.  The dummy's job is simply to act as the axle on which the billboard rotates.
DPH

I loaded two objects, a plane and a cube.  I parented the plane to the cube and rotated the camera, and the plane still spins around.  As I expected, limits have no effect, as rotational values do not change when the object is "pointing at".

Next I added a sphere (dummy) and a cube.  I pointed the cube at the sphere and the sphere at the camera.  Rotating the camera allows me to pan around the cube as if the dummy doesn't exist.  

Had I not seen the billboard trees in the marketplace, I'd be doubting they can be made in Poser.

hmm...I dunno...but when I have the eyes in a Poser render aligned with the camera, they 'seem' to follow you around the room. If you did that with a render, saved as a picture, then pasted it, would it work (I'm at work...but obviously can't check it right now...;)

I'm trying to create a simple one poly prop that always faces the camera.  I want to use it for the usual things like trees, and also for things like smoke rising in the distance, fog layers etc.  Until I can get the plane to face the camera automatically, no picture will work particularly well.

A search in freestuff turned up a set of amazon villagers, but the file appears to be corrupt.

Unless you are doing an animation it is easier to just rotate the props manually in top view to point at the camera. The more distant they are from the camera the less tilt you will get using point at.

Well, of course I could do that ;)

Works well for a prop or two, but the most common use of billboards is to have dozens or even hundreds of visually complex props in a scene.  Changing the orientation of a hundred pieces of shrubbery for each camera keyframe is exactly what I'd prefer to automate.

(Not worried about tilt as I plan to keep the camera low and pointed mostly at the horizon.)

Try applying 'Lock Actor' to the dummy helper.
DPH

There is a python script by Ockham that keeps billbaords facing the camera

Quote - There is a python script by Ockham that keeps billbaords facing the camera

Do you know where it can be found?

I'm not seeing it at http://www.ockhamsbungalow.com/Python/

maybe just send him a message and ask for it. I asked him for it, and he made it for me, but I don't know if he ever released it. At least I think it was Ockham, but this was at least three years ago.

sure sounds like Ocham. He recently made the NIFTIEST script for me on request!

Ockham rock! (buy something from him to appreciate it!)