Example of markers

[photoscan_user]

Where I can find example of cross and circle markers which are types in detect markers menu?

[James]

http://www.agisoft.com/pdf/PS_1.1_Tutorial%20(IL)%20-%20Coded%20Targes%20and%20Scale%20Bars.pdf

[photoscan_user]

Is there 3 types exist? or 1-2 is same type?

What if I know that on the UAV flight there was 5 markers, can I get top-5 most feasible markers by Detect Markers?

[Alexey Pasumansky]

Hello photoscan_user,

1 and 2 are actually the same.

If you mean autofinding the correspondence between the found markers (unsorted) and list with the coordinates, you can use Ignore Labels option in the Import CSV dialog when loading markers coordinates. PhotoScan will try to find the correspondences automatically and rename the markers in the projects according to the loaded list.

However, it works more stable, if you have considerable amount of markers, like 10-15 in the list.

[photoscan_user]

I was talking about detecting positions of markers on images.

Example of type of marker I want to detect in attachment.

I was trying to do it using "Cross(non coded)" type, but get very strange results (for example detected markers out of bbox of chunk), I have tried it with 10,50,90 for Tolerance parameter and get about the same bad results all the time.

[Dave Martin]

photoscan_user,

Having seen your example you're trying to detect, I think that the name used 'Cross (non-coded)' is possibly a bit misleading.  A better description for types 1 and 2 might be 'Quadrants (non-coded)' or 'Quarters (non-coded)'.  I don't think the example in your last post will be recognised as matching Type 1/2 (and your example doesn't have the contrast between similar-sized blocks of black and white as these types do).   I have used both type 1 and 2 with success, ranging in size from 5-gallon pail lids (painted) to fabric targets in excess of 1 metre square.

Dave

[Alexey Pasumansky]

Hello photoscan_user,

The example of your target doesn't correspond to "cross target" non-coded type supported by PhotoScan.

[photoscan_user]

I have tried to use recommended markers(see attachment), but false positive rate is too high to use it, so for now seems this feature is useless.

[Dave Martin]

I have tried to use recommended markers(see attachment), but false positive rate is too high to use it, so for now seems this feature is useless.

PhotoScan_user,

1) That doesn't quite match what the manual shows - have a look at the image James posted in response to your original request.

2) The feature definitely isn't useless, as I said

....   I have used both type 1 and 2 with success, ranging in size from 5-gallon pail lids (painted) to fabric targets in excess of 1 metre square.

If you are getting false positives when using the correct targets, suggest you post a couple of examples of those false positives.

Dave

[photoscan_user]

That doesn't quite match what the manual shows - have a look at the image James posted in response to your original request.

Do you mean that white/black should be mirrowed or this type of marker should have circle shape?

Anyway one example I have attached was detected, false positives were really unrelated like point on forest.

Is there any public data that I can use to test this feature?

[Dave Martin]

That doesn't quite match what the manual shows - have a look at the image James posted in response to your original request.

Do you mean that white/black should be mirrowed or this type of marker should have circle shape?

The black sections in your example are only triangles, they should be squares like the white. At the top of page 60 in the manual it explains "...a non-coded target looks like an ordinary full circle or a figure (circle / rectangular) with 4 segments....". Your targets effectively have 6 segments. Cut off all four corners, or make the black go all the way to the outside.

Anyway one example I have attached was detected, false positives were really unrelated like point on forest.

Can you share one of these example images?

Is there any public data that I can use to test this feature?

There is a sample data set on Agisoft's download page which will allow you to see target detection in operation, but that uses coded targets.