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Slow Image Target detection for large dataset (50+ targets)

June 26, 2020 - 8:29am #4


I am using Vuforia in Unity with a local database containing 140 Image Targets, each of which has a 5-star image target rating. Since updating Vuforia from 8.3.8 to 9.1.7, tracker detection has become very slow on Android devices. Sometimes it takes 10 to 20 seconds before the target is detected.

  • I've tested with printed targets in different light conditions and off my pc monitor, with the same results.
  • This is also tested on multiple different Android devices, including high-end phones.
  • This behaviour does not occur in the Unity Editor using a webcam, or on iOS, both those platforms have fast detection.
  • This behaviour did not occur when using Vuforia 8.3.8.
  • This behaviour occurs for both Mono and IL2CPP Android builds.

When reducing the number of image targets in the dataset, detection speed becomes better, but only reaches acceptable speed when going as low as 20 targets. From the documentation I understand that for datasets over 1000 targets, switching to cloud recognition is recommended, so 140 targets should not be a problem right?

I have tried upgrading to Unity 2019.4 and Vuforia 9.2.7, this yields no difference in detection speed.

Do you have any idea why target detection speed on Android is so slow?

Slow Image Target detection for large dataset (50+ targets)

June 29, 2020 - 1:58am #3


For Android we had a bug that was fixed with 9.1 in which if you would have build for ILCPP the loading time of the dataSet would be around ~20 seconds.

Yes, you are correct, we recommend a maxim of 1000 images for the db and the 140 should work.

Could you please share the database with us to test it? if you think the data shouldn't be shared here, please pm the download link.

Also, could you please let me know the device you used for testing? Model, os version?

Thank you.

Vuforia Engine Support


Slow Image Target detection for large dataset (50+ targets)

June 29, 2020 - 10:12am #2

Hello, thank you for your reply.

While I did notice increased loading time of the dataset itself, the main problem was the slow detection speed after the dataset had already been loaded. If I understand you correctly, that bug should no longer be present in Vuforia 9.1 or higher.

I will send a download link for the database file via DM.

The devices used for testing were:

Android (with which the problem occurred):

  • Motorola Moto G4
  • Motorola Moto G6
  • Oneplus 3 (Android 9)

iOS (which did not have the problem):

  • iPhone 7

kind regards,


Slow Image Target detection for large dataset (50+ targets)

July 6, 2020 - 2:03am #1


Have you had any progress finding the cause of the detection delay? As it stands Vuforia is useless to me as I really need those 140 targets, which is supposed to be well within the limits of what's possible for a local target database.

Please let me know if there is any additional information you need or if there's anything else I can help with.

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