# Align object after Motion Tracking: Edited

I am tracking an object in a video, which I want to replace with a 3D object in Blender. After tracking, I solve motion, and apply an object solver to the 3D constraint.

This is where I get lost. I don't know what I am supposed to do to get the computer to align the object, using the trackers I have placed, so that it fits the rotation and position of the original object in the footage. The only way I know of is to manually rotate and move my object, but I know there should be a more professional way to do this. Could you guys help me find my options?

P.S. I'm using Blender 2.8rc

Here is a picture of the object I am trying to replace with a 3D object. I am don't know how to get the computer to correctly place my object, using the trackers as shown on the image.

The 3D object I'm trying to replace the box with is almost the same size. I'm hoping that it's dimensions are close enough that it won't cause a problem, though. If it does, I'll make another model.

• IMO this question does not have enough detail and that's likely why this has't received much attention. It would be useful to add screenshots of your video and object to give this some context and to give some insight as to why you're finding it difficult to align it to the first frame. – Rich Sedman Jul 18 at 8:17
• I added some info, hope that helps. I purposely didn't add a picture of the object, though, because I'm trying to stay anonymous, and if I posted that 3D object here, I couldn't use it on a personal video. Hope that makes sense. The object is basically just a box-shaped object, anyway. – RBlong2us Jul 18 at 14:55
• Have you tried with fspy? You can extract the first frame, feed it to fspy, align axis in fspy, import the result in Blender – Kiskit Jul 18 at 14:59
• I would rather keep it all in Blender, please. – RBlong2us Jul 19 at 2:42
• is there any other detail I need to add to this question? – RBlong2us Jul 22 at 1:54

I do not fully understand your question, which is probably why it didn't receive much attention, but I'm still going to try to explain the problems that I do understand.

From what I understand, you go onto explain how you tracked the object in the video, and then ask how to align it now using the tracked info.

In the Tracking, after you have successfully tracked the object, under Reconstruction, hit Empty to Track.

After doing this, switch back to the 3d viewport, and then you will have a bunch of empties wherever Blender thinks your trackers were. You will find that these form a box (If you have tracked successfully. Also, you may need to take footage from other angles as well, and perform the same steps on them). If you did take footage from other angles as well, then delete the overlapping empties. Now, it is just a simple matter of assigning the vertices of your box to the corresponding empties.

Or, if that is too hard, then you could just do it by hand, which isn't too hard either.

Again, this is pieced together by what I do understand of your problem, which isn't a lot, because your question isn't quite phrased together too well.

I hope this solved your problem, and have a wonderful day.

• this isn't a blender related question, this is about motion tracking. there are hundreds of programs to help you with it. after effects has an automatic system for that. manual premiere: youtu.be/aRI1cjM1UHE and here's how you can do it directly in blender: blender motion tracking: youtu.be/xxMI4aT4FQQ if you don't like these motion tracking systems then the only alternative I know of is implementing your own. – Frederick Jul 24 at 3:16
• thank you both for your answers. @Arihan Sharma, I have a question for you. How would I assign the vertices of my box to the corresponding empties, and will this work if I have bevelled corners? I assume this won't deform my mesh? – RBlong2us Jul 24 at 15:36
• I've edited the question so that it better describes my problem. – RBlong2us Jul 24 at 15:48
• @RBlong2us The trackers will be used as primitive vertices, if that makes sense. As for the question concerning bevelled vertices, as long as you have not applied the bevel to your mesh (i.e it isn't part of the vertex data), you're fine off. – Arihan Sharma Jul 28 at 18:37
• sorry, that still didn't answer my question as to how to assign the corner vertices to the empties. – RBlong2us Jul 29 at 0:04