Topics

1

General / Did the SfM or Reprojection Error computation change?

« on: March 02, 2023, 06:12:16 PM »

Dear all, I have been processing photos with the old Metashape (v. 1.8.4).
Now, I have processed the same photos on the same PC with two different Metashape 2 releases. All images are identical, all processing parameters are identical, but still, version 1.84 gave me an RMS Reprojection error (RE) of 0.66 (2.8 px) and in the 2.0 releases, it is always 2.1 (6.4 pix).

I tested this with several datasets, and the RE is always much higher in the 2.0 versions. So, did the SfM algorithm change, the mathematical model behind the interior orientations or the way that RE is computed? I tested this with GoPro images (so fisheye model).

Cheers, Geert

2

General / Render to image files rather than video

« on: March 10, 2022, 02:57:45 AM »

Dear all,

I need to render artificial images from a textured 3D scene . I can create a camera path and then render that into a video file. However, I want to render the views from the camera positions to image files. Let's say I defined a path with 20 camera positions, so I want to end up with 20 images, each rendered from the defined camera positions. Right now, I make a video of 1 second that has a framerate identical to the number of camera positions, and then I extract individual frames. This is time-consuming and suboptimal, hence my question.

Thanks for any help! Geert

3

Python and Java API / Asking user multiple input in dialogue

« on: August 05, 2019, 02:20:46 PM »

Hi All,

I want to make a dialogue in which I ask the user something (with Metashape.app.getInt) and also ask if this should be applied on all the cameras or only the selected ones. So all this should be in one dialogue, not in consecutive ones. How can I program this? Does Metashape support this?

Cheers,

Geert

4

General / New book chapter on orthophoto production with PhotoScan Pro

« on: January 31, 2014, 12:10:55 PM »

Dear PhotoScan users,

For a recently published book on non-invasive archaeological survey methods (http://www.springer.com/social+sciences/anthropology+%26+archaeology/book/978-3-319-01783-9), the editors asked me to give an overview of the most recent ways of turning archaeological aerial photographs into accurate orthophotographs. Together with my co-authors, I used this opportunity to go into some details on both the imaging process as well as the Structure from Motion and Multi-View Stereo that follow.

In essence, we tried to tackle everything from data acquisition to final orthophoto product. This way, we elaborate on the “obliques versus verticals” debate in archaeology and how this relates to interpretation and mapping accuracy. Afterwards, it is explained which main factors result in geometrical image deformations (lens distortions, tilt and relief displacements) and how camera calibration tries to model the internal geometry of the complete imaging system (all terminology related to this field is explained as well). Afterwards the Structure from Motion and Multi-View Stereo steps are detailed and exemplified using PhotoScan. The idea was to not overload the text with technical details, but just mention enough jargon to make most ideas and concepts of this approach clear.

Despite many conversations, Springer still managed to introduce errors in some figures (lost capitalization on places where it matters, Greek symbols that became Latin symbols, displacement of some text), but nothing is so severe that it should hamper your understanding of the matter.

For those interested, the book chapter can be found here:
https://www.academia.edu/5901490/Undistorting_the_past_New_techniques_for_orthorectification_of_archaeological_aerial_frame_imagery
or here: https://www.researchgate.net/publication/259934911_Undistorting_the_past_New_techniques_for_orthorectification_of_archaeological_aerial_frame_imagery

The full reference of this book chapter is: Verhoeven, G., Sevara, C., Karel, W., Ressl, C., Doneus, M., Briese, C., 2013. Undistorting the past – New techniques for orthorectification of archaeological aerial frame imagery, in: Corsi, C., Slap?ak, B., Vermeulen, F. (Eds.), Good practice in archaeological diagnostics. Non-invasive survey of complex archaeological sites. Natural Science in Archaeology. Springer International Publishing, Cham, pp. 31–67. DOI: 10.1007/978-3-319-01784-6_3.

Best regards,

Geert

5

General / Some very nice archaeological examples

« on: September 15, 2012, 01:22:17 AM »

For those interested, a new article on the archaeological use of PhotoScan (in an excavation context) will be published soon. You can already look at the nice illustrations here: http://www.sciencedirect.com/science/article/pii/S0305440312003949?v=s5

Regards,

Geert

6

Bug Reports / Export Model

« on: April 29, 2012, 05:25:31 PM »

Hi PS users,

I have a 3D model of a Roman gate that I would like to export. The camera positions are known to 2 cm accurate by using D-GPS. The idea is that I have all the vertices of the model in the WGS84 or UTM-ETRS89 coordinate reference system. However, I am unable to do so. I tried almost all possible options (binary coding on and off, different formats, different coordinate reference systems) but the export creates:
* just lines, or
* very blocky models. Even stetting the precision to 20 does not seem to help.

Does anyone have a solution for this? Cheers,

Geert

7

Python and Java API / Amount of feature points

« on: April 24, 2012, 07:13:52 PM »

Hi all,

is it possible to use a Python script in which the amount of feature points per photograph are defined? Now, PS always uses the default maximum of 40 000, but I want to limit it to a precise number (so not using the general accuracy settings but for instance 25 000 per image).

Cheers,

Geert