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Tracking stability and accuracy improvements

April 9, 2014 - 5:19pm #1

I have been reading through a lot of forum posts here. I have tried to apply these solutions and additional settings provided by Vuforia, e.g. extended/persistent tracking. I still have two major issues with the SDK that limits its usability significantly. 

I am developing for the iOS and Android platforms in native code, not with Unity.

I hope to gather a collection of suggestions that I can try out to improve the experience. At this point I am really hoping for anything.

1. Being close to a marker and tracking causes model to jump/shake occasionally

It seems like the marker provided by the demo, e.g. stones is somewhat more stable than self created markers that have a rating of 5 stars. The model I am using is scaled up quite a bit beyond the size of the marker and at this point you can really notice that the model occasionally rotates over an axis for a few frames and then jumps back into position.

My solution so far was calculating an average of the last four pose matrices. That somewhat helps to avoid big jumps but also causes delays in actual position updates of the model when moving the camera.

Are there any other strategies that people have applied to get this more under control or something like a low pass filter? Also, what about the environment, what works best in regards to lighting, colours of the marker etc.

2. Extended tracking, moving camera around model moves model towards the camera

As soon as the camera is too far away to pick up the marker the extended tracking takes over, if enabled. The issues described under #1 doesn’t seem to happen here. I notice another issue here though. If I walk around the model, it seems to move always towards me a little bit. Let say you have a cube in a parking lot that fits perfectly between the lines. If I step far away and then walk around to see the cube from the side, the cube will move towards me over the line of the parking spot.

I understand extended tracking is creating some sort of map from the environment and tries to place the model based on this map. Is it expected that this is just not 100% accurate, or is there something I can do, like a dynamic offset etc, to account for this?

Again, any other leads, suggestion or links to other posts would be highly appreciated.

Thank you.

 

Tracking stability and accuracy improvements

April 12, 2014 - 10:24am #4

The biggest concern is the shifting/moving of the model above the marker when moving around while in extended/persist tracking mode. What would be approaches that could improve behaviour? Even it is a hack for specific situations..

My impression / understanding (based on your description) is that you are probably simply reaching the "limits" of what Extended Tracking can do... the developer guide tries to explain what are the intended use cases / scenarios, and what are the limitations to be aware of.....   as I said, you could still try playing with/without persistent tracking on to see if it makes a difference, but beyond this, I am not aware of specific tricks / hacks or other workarounds (beyond what is already described in the developer guide)...

Sorry if I cannot help much more on this.

 

Tracking stability and accuracy improvements

April 11, 2014 - 12:38pm #3

Hey Alessandro,

thank you for your reply.

I definitely read the post in the knowledge base about extended tracking, as well as the persist tracking option etc.

I am also sure I can find some instructions/code samples about low pass filters.

But what I am more looking for is suggestions about what worked best for people, what has been tried and what are experimental approaches, hacks and solutions I could look into and evaluate. I am not so much looking for code, rather some suggestions and/or any leads.

The biggest concern is the shifting/moving of the model above the marker when moving around while in extended/persist tracking mode. What would be approaches that could improve behaviour? Even it is a hack for specific situations. Anything at this point would really help.

Thanks. 

Tracking stability and accuracy improvements

April 10, 2014 - 12:48am #2

About low-pass filters, if you search the Forum, you should find some threads discussing this topic (various developers have tried something in this area);

althouh, I cannot recommend a specific or "best" approach on low-pass filtering techniques, as this is a bit off-scope for this Forum.

 

Concerning Extended tracking accuracy, I would say that a 100% accurate tracking cannot be realistically expected in a general case; the actual accuracy may vary significantly depending on the amount of detail in your room or testing envorinment; lighting conditions can also play a role, of course.

For more details on Extended Tracking, please also take a look at this page:

https://developer.vuforia.com/resources/dev-guide/extended-tracking 

 

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