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Messages - Lia

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1
General / Re: Changed pitch and markers error in meters increased
« on: December 08, 2022, 04:00:14 PM »
Here is a screenshot of the problem

2
General / Changed pitch and markers error in meters increased
« on: December 08, 2022, 03:54:57 PM »
Hi, I had to change the pitch of my model. When I did it, the Markers error (m) increased from 0.00Xm to 4-25 m. Is there a way to automatically correct the marker's error without setting each market individually?

I have hundreds of markers.

3
General / Re: Wrong orientation after alignment
« on: August 31, 2021, 03:35:02 AM »
Hi Paulo,

Yes, 45° pitch seem to work better for this reconstruction. Thanks for your help, I appreciate it!. I send the reports attached. However, I am quite concerned since the structure ("cliff") looks vertical when setting the pitch at 45° (see the screenshot attached). I expected a forward-looking camera setup on the ROV, but it seems like it had a certain angle. Is it what the pitch of 45 ° indicates?.
I will reconstruct many vertical structures, so I will need to understand why to set the pitch at one or another degree.

I am also thinking about the calculation of yaw. In the end, we let it as zero, but it wasn't zero according to the calculations using the coordinates. Why is the model working with yaw set at 0°?

I hope you can give me some insights to understand the logic behind the results that we obtained.

Have a great night.

Best regards,

Lia

4
General / Re: Wrong orientation after alignment
« on: August 30, 2021, 09:11:37 PM »
Hi Paulo,

Thanks for the detailed explanation. I set pitch 90° and check yaw. I am sharing the new CSV with the mentioned changes and precision 8. However, the model is bent forward if I set pitch at 90°, as you can observe in the screenshot I share.

The frequency rate of the video is 25 FPS. From which we extract one frame every second.  The ROV moves continuously at a similar but not identical speed (moving a few centimeters every second).

Kind regards,

Lia

5
General / Re: Wrong orientation after alignment
« on: August 30, 2021, 01:08:31 AM »
Hi Paulo,

Setting the pitch to 90 degrees does not produce the best reconstruction. Alexey suggested setting yaw in 0 and pitch in 90, and the model looked good. However, 30 degrees pitch and 0 degrees yaws were the best. Still I want to make sense of why to set the values in one or another way. I should have transformed the yaw values to degrees. In that case, the values are very different from zero. I send the document attached.

Kind regards,

Lia

6
General / Re: Wrong orientation after alignment
« on: August 27, 2021, 11:55:16 PM »
Hi Paulo,

Regarding your question about USBL, we use Global Acoustic Positioning System (GAPS)

The accuracy is 1% of the depth in our case. However, some recent GAPS equipment can be even more precise https://www.ixblue.com/products/gaps-series

Kind regards,

Lia YS

7
General / Re: Wrong orientation after alignment
« on: August 27, 2021, 11:50:56 PM »

Hi Alexey and Paulo,

As I mentioned in the previous message, I send the screen shots of the model with yaw 30 degrees.

(and an additional side view of the model with yaw at 0 degrees 1_Yaw0_Pitch0_D7_B_sideview)

Kind regards,

Lia YS

Hi Alexey and Paulo,

Thank you so much for the advice. The problem seems to be solved. However, I have a few questions about the pitch.

But first, this is what I did and the correspondent screenshots and reports.

*I set the pitch at 0. I checked the yaw boxes (except the southeast cameras), and I set yaw at 0 degrees.  Attachments: 1_Yaw0_Pitch0_D7_B_frontview, Report_D7_461_B_lat_long_yaw0 (Notice that: the camera location total error is 5.4m)
*I set the pitch at 0. I calculated the yaw using the coordinates (as described by Paulo), range (-1.18 to 1.57 degrees). Attachments: 2_Yaw-calculated_Pitch0_D7_frontview, Report_D7_461_B_lat_long_yaw_exact_pitch0 (Notice that: the camera location total error is 5.4m)

The models have the front view as desired. However, why are we setting the pitch at 0 degrees?. The camera in the ROV does not have a downward-facing set-up as assumed when setting pitch at zero (https://www.agisoft.com/forum/index.php?topic=10515.0). It is because the structure recorded has a steep slope, so the camera has a forward-facing setup.  However, the pitch set at 90 degrees does not produce a good result, as observed in the initial post. The pitch at 0 degrees, as you advised, works. However, the side-view of the model is less steep than I would expect. I have tried different "pitches," and a 30 degrees pitch produced a model that seems to fit the best (camera location total error 4.39m). However, this is my empirical view.
Regarding the previous I have the following question:
Would you suggest letting it in 0 or in 30 degrees and why ?.
How pitch works in Metashape? is Metashape very sensitive to a not precise pitch?
Is there a way to calculate it?
(I will attach the report and screenshots of the model setting pitch at 30 degrees in the next message since this platform only allow 4 attachments at the time)

Note: In every case, I had to resize and rotate the region. Metashape always gave me a sideways or upsidedown region. I don't know why.

King regard,

Lia YS

8
General / Re: Wrong orientation after alignment
« on: August 27, 2021, 11:42:35 PM »
Hi Alexey and Paulo,

Thank you so much for the advice. The problem seems to be solved. However, I have a few questions about the pitch.

But first, this is what I did and the correspondent screenshots and reports.

*I set the pitch at 0. I checked the yaw boxes (except the southeast cameras), and I set yaw at 0 degrees.  Attachments: 1_Yaw0_Pitch0_D7_B_frontview, Report_D7_461_B_lat_long_yaw0 (Notice that: the camera location total error is 5.4m)
*I set the pitch at 0. I calculated the yaw using the coordinates (as described by Paulo), range (-1.18 to 1.57 degrees). Attachments: 2_Yaw-calculated_Pitch0_D7_frontview, Report_D7_461_B_lat_long_yaw_exact_pitch0 (Notice that: the camera location total error is 5.4m)

The models have the front view as desired. However, why are we setting the pitch at 0 degrees?. The camera in the ROV does not have a downward-facing set-up as assumed when setting pitch at zero (https://www.agisoft.com/forum/index.php?topic=10515.0). It is because the structure recorded has a steep slope, so the camera has a forward-facing setup.  However, the pitch set at 90 degrees does not produce a good result, as observed in the initial post. The pitch at 0 degrees, as you advised, works. However, the side-view of the model is less steep than I would expect. I have tried different "pitches," and a 30 degrees pitch produced a model that seems to fit the best (camera location total error 4.39m). However, this is my empirical view.
Regarding the previous I have the following question:
Would you suggest letting it in 0 or in 30 degrees and why ?.
How pitch works in Metashape? is Metashape very sensitive to a not precise pitch?
Is there a way to calculate it?
(I will attach the report and screenshots of the model setting pitch at 30 degrees in the next message since this platform only allow 4 attachments at the time)

Note: In every case, I had to resize and rotate the region. Metashape always gave me a sideways or upsidedown region. I don't know why.

King regard,

Lia YS

9
General / Wrong orientation after alignment
« on: August 24, 2021, 04:16:43 PM »
Hi everyone,

I have aligned about 244 images that have considerable overlap. I upload the external reference for each image. However, the point cloud default frontal view (xyz) shows the model from one side, not the frontal view. When I align the same images without coordinates, Metashape seems to do better work.

I have used the Lat long coordinates in decimal degrees WGS84 and run the alignment.  I have also transformed it to UTM. However, the final result is the same.

I have modified the default accuracy to the accuracy of the "GPS" used (see image attached). Because the structure modelled has a steep slope, I have tried pitch 0 and pith 90, but it did not improve the orientation of the point cloud.

I attach the reports of the models with different in ( GCS WGS84, UTM N25, no coordinates, screenshot). Hence, you may be able to see what is wrong and how can I fix it.

I am looking forward to getting advice from the Agisoft Metashape experts.

Thank you,

Lia

10
General / Re: Vertical structure orientation, external reference
« on: August 18, 2021, 12:40:03 AM »
Hi everyone,

Thank you to all of you for your comments. I appreciate it.

The change is very subtle because the ROV is moving slow and mostly vertically. So it can be possible to have a few seconds of video where there is no change in latitude and longitude but altitude (vertical movement). I have attached a pdf with the images, and as you can see, the movement mainly was in altitude (depth), and the images are overlapped.
However, the coordinates labelled as UTM are indeed incorrect. There is very little lateral movement, but there is movement. I will find why those numbers were labelled as UTM_long and UTM_lat.

To solve the problem, I verified that the latitude and longitude in Geographic Coordinate System GCS are correct (see attachment). Then, I uploaded the long and lat  (GCS_WGS84_N25) per each image in Metashape. After that, I used the convert tool in Metashape to obtain the correct UTM coordinates. So far, it worked.

If anyone has any valid objection regarding converting from geographic to projected directly in Metashape, I will appreciate it if you let me know.

Best Regards,

Lia

11
General / Re: Vertical structure orientation, external reference
« on: August 16, 2021, 09:57:13 PM »
Hi Paulo

It is impossible to tell that from the screenshot. The number of Frames is 592; It is impossible to see the reference complete in the screenshot. The reconstruction is of a large structure (tens of meters)
You are observing UTM coordinates and depth (XYZ). Of 14 consecutive images, it is 14 seconds (one image extracted per second from a 30 fps video)

I can confirm that the longitude latitude and depth (xyz) are different. However, I send a screenshot of the ArcMap so you can observe it.

I will write an additional post after this answer with extra information.

12
General / Fragmented reconstruction (underwater)
« on: August 16, 2021, 05:34:23 PM »

Hi everyone,

I will appreciate the answer of one of the experts of Agisoft Metashape Pro.

I am sending a detailed explanation that includes the screenshots of the problem briefly described here. I believe it is essential to understand what I refer to.

Description:
The following reconstruction corresponds to an underwater feature video recorded by ROV (28 frames per second). One frame per second was extracted to use in this reconstruction.
Number of frames (images): 592
In the 10 mins video, 26 USBL (Ultra short baseline) positioning was recorded. The USBL positioning was upload in R to obtain positioning per second of each frame grab extracted (1per sec) and exported as CSV. This CSV was used in Agisoft Metashape Professional (64bit) to reference the images.

Problem: when aligning the images, I get the message some images failed to align. And the alienation jumps spaces within the reconstruction. like if the video was not continuous, but it was. (Fig 1)

Questions:

Why is the reconstruction fragmented while the video where the images come from is continuous?
Why are the small chunks of images upside down?
Why are some cameras only used in the reconstruction when I used the reference, not when I aligned without a reference?

13
General / Re: Vertical structure orientation, external reference
« on: August 16, 2021, 02:39:43 PM »
Hi JMR,

I send attached the default view. Logically I can manually rotate it  (also attached). But, is there a way to modify the initial view. I will use this dense point cloud in another software to derivate terrain variables (rugosity, slope, orientation)  and the rotated exes xyz may not produce the optimal results.

The pictures used came from an ROV, and the coordinates from a USBL (Ultra-short baseline acoustic positioning system)

I applied the 90 pitch in the way that you suggested but the results were the same as the attached scream shots.

Kind regards,

14
General / Vertical structure orientation, external reference
« on: July 06, 2021, 04:14:27 PM »
Hi,

I am working with a set of images extracted from a video transect along a underwater vertical wall from recorded from the bottom to the top.
The georeferenced positions  of each image were extracted from an external device (USBL). It is relatively accurate and my point and dense cloud are fine.

But the xyz orientation is incorrect. How can adjust the settings to  account for the forward facing setup of the camera (as opposed to the assumed downward facing camera used in aerial photography).

A published papers mentioned that they add a pitch of 90 degrees (However, they used Agisoft PhotoScan  no A Metashape). The only way I found to add pitch was on the imported reference option. So I add a column in the reference table called pitch  with values of 90 per each row. For instance the reference table added had longitude latitude attitude( in my case depth) and the extra column called pitch.

Agisoft Metashape imported all the values for my coordinates but not pitch and the model of the wall shows a horizontal orientation instead of the actual vertical one. What should I do to get XYZ orientation corrected?

Thank you for your time and help.

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