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Initial scale in z-space

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Gene FeliceInitial scale in z-space
by on Aug 25, 2013 at 7:46:05 pm

Hello: I want to place an object in 3D space. I want the object to start in a specific place in z-space and at a specific size. Problem is, when I move the object back in z-space to the place I need it, it gets smaller. When I scale it up to get it to the size I need, it gets larger but also moves forward in z-space.

How can I place an object in the correct z position in the scene and then scale the object so that it stays in the proper z position but is the correct scale.

Thanks in advance.


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Roland R. KahlenbergRe: Initial scale in z-space
by on Aug 25, 2013 at 8:02:54 pm

[Gene Felice] "When I scale it up to get it to the size I need, it gets larger but also moves forward in z-space."

This sounds like a user-error. I suggest that you scale the layer by changing the Scale property in the Timeline instead of the Comp Panel.

HTH
RoRK

Intensive mocha & AE Training in Singapore and Other Dangerous Locations

Imagineer Systems (mocha) Certified Instructor
& Adobe After Effects CS6 ACE/ACI


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Darby EdelenRe: Initial scale in z-space
by on Aug 25, 2013 at 9:20:18 pm

[Gene Felice] "When I scale it up to get it to the size I need, it gets larger but also moves forward in z-space."

This should not happen unless you have set the anchor point to have a non-zero Z value. Check to make sure that you have the third component of your anchor point set to zero. Also make sure that you are, in fact, scaling as Roland suggested.

Darby Edelen


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Gene FeliceRe: Initial scale in z-space
by on Aug 26, 2013 at 12:19:45 pm

Hello: Thanks for the replies but they do not seem to solve my issue. Being new to AE I am sure I am doing something wrong but I have no idea what. Please let me go into detail as to what I have done in the hopes that someone can assist. I have a photo of my street that i added to a composition. I added a grid and oriented it so it lays on the street. As a test I created a shape layer with a rectangle. I set the shape layer to 3D. I moved the rectangle back in Z space to a specific point on the street grid. I then scaled the rectangle up to the size I wanted. I now had the proper size rectangle at the proper z position. All worked as expected. Problem is it's not a true 3D rectangle and if rotated to the side becomes a flat layer. Now to the problem. I have a 3DS Max model of a helicopter in obj format. I tried to import it into AE, no go. I then found a Creative Cow tutorial called Importing 3D models into Adobe's After Effects. It showed me how to use Photoshop to convert the model to PDS and import it. Worked great. I now have a 3D helicopter in my composition that looks and acts just like a real helicopter. I now moved the helicopter to the proper point on the street grid. Problem is that point is further back in my scene so when I move it back it starts to look like a toy helicopter. I then assumed I could just scale it up like I did with the shape layer but no mater how I scale it also gets closer and changes position on the street grid. Obviously there has to be some way that I can have a 3D object in the scene at s specific location and size. Thanks for any help.


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Darby EdelenRe: Initial scale in z-space
by on Aug 26, 2013 at 2:41:53 pm

Ohhhhh, Photoshop 3D! That changes everything :)

Photoshop 3D layers are not 3D layers, or at least they shouldn't be. The way those layers work is by using a control null that defines the position/scale/orientation of the object. Use that null to move/scale/rotate your object and don't enable the 3D switch on the photoshop layer. The photoshop layer must be a 2D layer in order to properly project the rendered 3D object onto the screen.

Also, the only AE releases that this feature currently exists in are CS5 and 5.5. It was removed from CS6 because the Photoshop 3D implementation changed significantly and has not made it to AE yet. So if you're using any version but CS5 or 5.5 then your Photoshop 3D layer isn't even really a Photoshop 3D layer.

Darby Edelen


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Gene FeliceRe: Initial scale in z-space
by on Aug 26, 2013 at 7:32:26 pm

Hello:
I was using Photoshop only because I needed some way to see if I could accomplish my goal without spending money to find out that I could not. My plan is to purchase Elements 3D from Andrew Kramer. Problem is, when I look at his demo it seems that he basically does the same thing and uses a control Null.

My way of thinking is this: An object should have and X & Y. In 3D also a Z. The further back in Z the smaller the object would appear in the composition. That said, the object should also have a scalable size. If I took a 3DS Max model of a building and used it twice in my comp. I put both building on the same Z plane. They would both be the same size. However, if I wanted one of the building to be a much larger building I could simply sale it up. It would still be sitting on the same Z plane, it would just be a bigger building. Is there some flaw in this? I ask because now matter what parameters of the objects I adjust this does not work
Thanks


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Darby EdelenRe: Initial scale in z-space
by on Aug 26, 2013 at 10:51:06 pm

The Control Null is not itself a limitation, it's the work around of a limitation.

Any effect that renders 3D internally (the effect renders a 3D object/system) including many of the Trapcode effects (Particular, Form, etc.) and Element 3D needs to be applied to a 2D layer. The effect is responsible for rendering in 3D perspective based on the composition camera's view and the effect must assume that it is on a 2D layer to do so.

If you apply these effects to a 3D layer they will not render properly.

The Control Null is a way to 'place' the object in AE's 3D space. This way you can apply the effect to a 2D layer and still have an After Effects based 3D control to place the object in perspective. You only use effect controls or a 3D Control Null to place objects this way, you never move the 2D layer.

If you are still confused you'll have to be more specific or upload pictures.

Darby Edelen


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Gene FeliceRe: Initial scale in z-space
by on Aug 27, 2013 at 12:15:43 pm

Hello:
I will try to be more specific. First some background info. My grandson and I are both into special effects and "how did they do that". About a year ago I picked up AE and, as something we could do together, we have been learning AE and using it to do effects. We have done many of the Creative Cow and Andrew Kramer effects with reasonable success. Because GI Joe came out we thought a helicopter landing in the culdesac I live on. We found a 3DS Max obj helicopter sequence on line. We took a photo of the street from my front porch. We animated the helicopter to fly in from a distance, hover over the street, rotate a bit so it was clear the helicopter was not 2D, and land. All want well and looks great. Problem is the helicopter is to small and doesn't look real because there are cars, etc parked on the street that are larger. My though was all I need to is scale the helicopter up. When I scale it up it gets larger as expected but also appears to move closer. By the time I get it large enough it is sitting in my front yard and not the street. If I look at the 3D scene in top view it shows that the helicopter has not moved in Z space. It is sitting at he same spot I placed it. However, from front view the helicopter has moved closer. Not only is it larger but it has moved completely off the street and into the front yard. No matter what I do I can not get the helicopter to stay visually in the center of the street and get larger. It seems to me that placing a 3D object into a scene at a specific spot and size would be a common task but I can't seem to make it work. I thought that maybe I needed a larger 3D model and that the scaling needed to take place in 3DS Max so I found a larger 3DS model of a truck and tried it. Same problem. Any assistance would be great. Thanks


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Darby EdelenRe: Initial scale in z-space
by on Aug 27, 2013 at 2:37:18 pm

Okay.

You're describing scaling. It's not moving forward at all. It's just scaling. The important piece of information in your description is that it's not actually moving at all in the top view.

Most likely the problem you're having has more to do with the anchor point (the point from which a layer scales). Anchor Points default to the center of a layer which causes them to grow along all axes (X,Y & Z) when scaled, which sounds exactly like what you've described.

If you move your anchor point (or the anchor point of the control null) to the bottom of the helicopter (to its landing gear) before scaling then your helicopter will scale away from its bottom and appear larger while still "landing" in the same spot.

Another thing to consider is the camera you took the photo with may have a different field of view (zoom) than the camera you have in your After Effects composition. This can effect the relative sense of perspective.

Darby Edelen


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Gene FeliceRe: Initial scale in z-space
by on Aug 27, 2013 at 4:32:55 pm

Hello:
Thank God for people like you. I moved the anchor point to the landing gear and now scaling works as I would have expected. After seeing the problem it now makes perfect sense. It now is very clear as to why the scaling did what it did. Thanks again !!!!!!


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