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linking null with expressions error
Hopefully this is the last question of the day. I am linking the point of view with expressions from a camera to a null. When I do this with the pick whip I get and error and the expression says thisComp.layer(“Null 3”). If I type in “.transform.position” after (“Null3”) the null only reacts to it’s position settings. I need to somehow create a birds eye view (looking down). HELP!
Thank you,
Heather
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6 Replies
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I don’t quite understand your post.
You want to use a null as the camera’s target?
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*** make sure your null is 3d
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Yep , it is. But I’m still not able to get above the object and look down….any other thoughts??
THANK YOU!
Heather
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Sorry…I wasn’t too clear. I have a camera, and I have a null in 3-d. I set an expression in the camera layer point of interest to a null, so that the null will move the camera’s point of interest. Hope that makes more sense! I’m just trying to look down from up in the sky on some type, but seem to figure it out.
Thank you,
Heather
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Heather,
If I understand correctly, this may help…
In order to link the camera’s point of interest to the null’s position, you need to alt-click on the stopwatch for the Camera’s Point of Interest button. Select the pickwhip (the curly que) and drag it to the Position property of the Null. Don’t select the numbers of the Position property because you will link only the x,y, or z values.
In order to have your “birds-eye view” you need the camera to be directly above your null. Position in 3D at will. You can use the Left and Top views to make sure that you get the camera positioned appropriately.
You can also link the position of the CAMERA to the position of the NULL. Using a bit more math, you can make it so the camera hovers directly over your null but a set distance away. Try this:
in your Camera’s Position property, alt click the stopwatch and type this.
x = thisComp.layer(“Null 1”).transform.position[0];
y = thisComp.layer(“Null 1”).transform.position[1]-400;
z = thisComp.layer(“Null 1”).transform.position[2];
[x,y,z]What this tells your camera to do is to use the x, y, and z coordinates from the null as the x, y, and z coordinates of your camera WITH ONE EXCEPTION. They y position will be 400 pixels less than that of the null. Assuming you haven’t rotated you null, this will place the camera 400 pixels ABOVE your null, giving you a birds-eye view.
Now, rotating nulls and other layers will change all of this, but you can apply the same math above to both the x and z values and put your camera wherever. Now, when you move your null, the CAMERA point of interest AND the position will move in concert.
Viola.
Hopefully that helps a little bit…
Jacob
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Thank you sooo much Jacob. I’m going to try that now!
Heather
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