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From 6.2 to 7.5 : Coordinate system hell

October 16, 2018 - 7:39am #1

Hi,

I'm currently trying to migrate my application from Vuforia 6.2 to 7.5 and I do not understand how coordinate system have been changed : 

According to this documentation https://library.vuforia.com/articles/Solution/how-migrate-vuforia-7_2.html I understand that camera have its own pose, Image tracker too and both are relative to a new World coordinate system.

But, looking at the documentation, when I'm trying to get camera's position in the ImageTraker coordinate system, documentation remain unchanged from 6.2 : https://library.vuforia.com/content/vuforia-library/en/articles/Solution/Working-with-the-Camera.html#How-To-Determine-Camera-Pose

 

So, How can I get the (M)VP matrix from ImageTracker now with 7.5 ?

 

Thanks for your help !

From 6.2 to 7.5 : Coordinate system hell

October 29, 2019 - 9:40am #9

Is it possible to get the camera distance from the image target (X,Y,Z values) as real distance in meters and show them on screen even if the camera is not in from of the image target?

From 6.2 to 7.5 : Coordinate system hell

November 28, 2018 - 5:27am #8

Hello,

I let this issue behin me to works on a few other things, but know time has come and I really would like to make my Vuforia's migration from 6.2 works.

Here is the 7.5 diagram : 

Do you have the equivalent with 6.2 ?

It would be very useful to understand the changes in the coordinates system.

 

In 6.2 I just get pose of the trackable result, convert to GLMatrix, then (as the doc explained) inverse and transpose thos matrix to have camera's matrix. 

in 7.5, when I'm not using DeviceTracker, what are the differences ?

Thanks in advance.

Regards,

    Vince

From 6.2 to 7.5 : Coordinate system hell

October 18, 2018 - 10:30am #7

Hello,

Thanks for the detailed response. Apologies but this is not my strong suit and I'm trying to translate the answers I'm getting from the dev team.

As explained to me, the Device Pose is the Camera Pose. If you want to calculate the pose of the Image Target relative the Camera Pose (as done before the coordinate system change), then you only need to look to the Image Targets samples for an example. My understanding is that this has been demonstrated in code.

I believe to move forward effectively on this topic, it would be best if you could refer your future questions about this relative to our current samples. This will help me to better communicate with the dev team.

Thanks,

Vuforia Engine Support

From 6.2 to 7.5 : Coordinate system hell

October 18, 2018 - 1:33am #6

Hi,

Sorry, I'll try to explain better : 

For my Vuforia usage, I need to get camera's position/orientation from tracked Image. When the image is tracked, I virtually consider the image as the 0,0,0 of the World coordinate system.

With Vuforia 6.2 I use MatrixUtils.transpose(MatrixUtils.inverse(state.getTrackableResult(i).getPose() )) to get a camera matrix in the World/Image coordinate system. Form the matrix I easily extract Camera position, direction and Up with matrix columns.

 

With Vuforia 7.5, according to this drawing, there is a World coordinate system. 

So when I'm trying to get Device camera's matrix in the Image coordinate system, how can I do ?

So I need to get Device Pose and Trackable (ImageTarget) Pose, and just multiply them, then inverse/transpose to get final Camera matrix ?

Thanks for your help.

Vince

From 6.2 to 7.5 : Coordinate system hell

October 17, 2018 - 4:00pm #5

Hello,

Confused by your response. Perhaps if you can describe what you're trying to do, or what information you need from Vuforia, we can better help.

Thanks,

Vuforia Engine Support

From 6.2 to 7.5 : Coordinate system hell

October 17, 2018 - 12:24am #4

Hello,

Thanks for this answer, I'll have a look right now.

Anyway, could you give me a little bit of details about World and Pose ? 

I mean, before I was only using ImageTracker pose to have MVP matrix, do I need to use Camera/Device pose + Image tracker pose + anchor pose now ?

Thanks for your help.

Regards,

     Vincent

From 6.2 to 7.5 : Coordinate system hell

October 16, 2018 - 3:21pm #3

Hello,

While we review the documentation separately, it was suggested that you review our samples (Image Targets feature): https://developer.vuforia.com/downloads/samples

In the samples we use the device tracker as the View matrix, which later we combine with the Model matrix (or the trackable result pose). For instance renderModel(projection matrix, view matrix, model matrix, textureIndex) in ImageTargetsRenderer.java

Thanks,

Vuforia Engine Support

From 6.2 to 7.5 : Coordinate system hell

October 16, 2018 - 2:49pm #2

Hello,

This may be an oversight in our documentation not being updated. Let me investigate further and I will respond back here.

Thanks,

Vuforia Engine Support

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