Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Messages - SimonBrown

Pages: [1] 2 3 4
General / Re: Lens not detecting chess board
« on: July 28, 2022, 10:25:08 AM »

Is there a way to manually calibrate the lens - trying to place points at the cross points of the checkers board?
If not, can i use calibration information from a different zoom? (I suspect not...)

Finally, I guess one other question. I have read that the automatic "calibration" when optomizing the camera positions is very good - so is it OK to not manually calibrate the lens?

The attempts I'm aware of - to manually calibrate a lens underwater using a chessboard - have proved unsuccessful.

Some observations:

Using a differing zoom to calibrate...will not ensure the path of light through the glass is consistent with the as-shot images used for reconstruction. Not recommended.

Metashape is very good with automatic calibration. There are some instances when manual calibration really pays off - we have provided consulting services to one massive civil engineering project client in North America on this - but the use case here sounds different.

ROV cameras can be a mixed bag...some good...some good at providing a visual feedback to the operator...but not all are going to deliver a result for photogrammetry.

So...some questions:

What camera is the lens attached to?
Are you shooting stills?
Or extracting frames from video?

General / Re: Processing large numbers of images - advice needed!
« on: February 14, 2022, 02:15:16 PM »
We have done some consulting work with the US National Parks Service such as this:

Happy to discuss further, if interested? Please use the Contact Us page:

General / Re: Using external drives (USB)
« on: February 02, 2022, 12:18:56 PM »
3.- Is it better to load pictures from one drive and write the project files on a different one or to do load the pictures and process the project on the same drive? (either built-in or external USB drives)
4.- Does the use of SSD drives improve the processing speed on any way?

Occasionally I forget to copy source images from a network share to the local SSD.

Things slow down you could say...but compared with other steps in the overall workflow its not hugely significant.

Its been so long since I used a mechanical as opposed to SSD for processing I cannot remember, but read/write speed isn't the greater bottleneck.

Processor speed and availability (or not) of GPU would be applying the limits.

General / Python Scripting Capacity and Capability
« on: January 17, 2022, 11:47:42 AM »
Both Jose and myself are delighted to announce that AccuPixel now has python scripting capacity and capability.

Its taken a while but we have taken the step to develop some in-house talent..

If you have a scripting requirement - automation/data manipulation/ocr text extraction as just a few examples - then please use the Contact Us page:

We look forward to hearing from you.

General / Re: Force Metashape to use manual tie points in Aligning
« on: December 19, 2021, 12:27:26 PM »
A minimum of 5 tie points are required for manual alignment.

Remember two things; firstly sequential really works best when used in conjunction with other parameters - specifically high accuracy GPS position data - and secondly sequential will not align images across parallel tracks. The step you see in the surface is therefore expected.

Suggestion; Run sequential. Then re run alignment with sequential off (generic) and reset alignment ticked off. This should at least align parallel track images.

As for bad qualify photos...they should be removed from the project and play no part in reconstruction.

General / Re: Photogrammetry with thermal images / water
« on: December 03, 2021, 12:11:24 PM »
The banks of the river - all things being equal - will be point-rich and align.

Are you using a drone? If the width of the river is not too great then a flight at altitude where both banks are visible might align to make a single model.

There is a risk with this as tie points may become clustered...not good.

The river itself? This will be interpolated, where the mesh grows its boundaries until either it a) meets another piece of mesh, or b) the bounding box or c) the algorithm calls a halt.

So the data in the river would be made might be possible to extract data from the aligned images. We are doing this with some data embedded in the jpeg (actually in the pixels...) and pulling it into machine readable format...

But without seeing the source data and understanding what the outputs are the above may be relevant...or not. Can you share anything?

General / Re: How to straighten a 'banana' scan in MS Std?
« on: December 01, 2021, 01:11:46 PM »
Curvature on long & thin objects is a common theme. Most are unaware their creation is...bent.

Fixing it might be possible...its not something I have encountered in my own work but here goes:

Constraints - requires Pro
Calibration - take a robust section of another chunk that does not show curvature and export the camera calibration. Then load it into this project. It *might* work. It might not. With calibration having constraints always helps. The problem with the std version is we won't really know how curved, or not, the section is - there is no way of validating what has been created.

Curvature is best avoided by doing long, thin runs.

General / Metashape Collision Investigation Webinar
« on: November 24, 2021, 08:19:02 PM »
Next month I will be delivering a webinar on using cost effective kit for #photogrammetry in conjunction the Insitiute of Traffic Accident Investigators.
An overview of Agisoft's Viewer and its benefits will be included too.

Its an event open to all and free. More details, including a link for registration, here:

General / Re: Seabed mapping -> alignment of 100.000 pics
« on: November 19, 2021, 06:34:05 PM »
By "patches" do you mean separate chunks?

General / Re: The Viewer Comes of Age
« on: November 08, 2021, 06:16:51 PM »
What's the best format to export out of Metashape Standard, for viewing a vertex coloured shaded model, or the textured model in Viewer?

The real step-change for the viewer is the ability to measure, interrogate and analyse the model and for this a scaled and (optionally) geo located model is required.

Apart from "It looks like this" - which in itself can be of some value - the standalone viewer can't really do much more than online viewing tools when it comes to handling Metashape Standard output I'm afraid.

Opitmising images, scaling, geo referencing and the accompanying outputs are what the Pro version delivers and what the Viewer is now designed to handle and work with.

As for what format...OBJ, FBX...whatever really. Some are physically smaller than others, but not tested every variation.

General / Re: Processing a massive underwater photoset without GPS
« on: November 06, 2021, 02:21:09 PM »
The troublesome scan i was testing with Sequential, it failed to align 2/3 of the cameras, rather than a the 10% before.  I'm guessing because the sequence was 'broken' by a run of a few bad quality cameras..

Sequential really is aimed at automated and machine executed missions. Breaking the sequence will break consecutive alignment.

When is using Estimated for a 2nd run of Align Photos worth doing?

Every time you use sequential. Make sure Keep Tie Points is checked in preferences. Estimated will then cross-align the images.

And thinking back to a scan from yesterday, it did have the last section of the scan shooting off on a completely wrong plane...  So i selected all of those cameras and realigned them, and they then aligned great...

Check the number of tie points in the Reference pane for these cameras. If its less than 100 then consider their alignment weak and likely to see them removed during recursive optimisation - which is required if accuracy of output is a goal.

I'm having to live on less than £10 a day at the moment, as I'm proper skint now.  So i'm stuck with the cameras and hardware i already had

Dont change your kit. Change your capture method. Do you really need all those images? Or could a lesser amount do? Process and align what is needed - this will save time.

General / The Viewer Comes of Age
« on: November 05, 2021, 04:24:56 PM »
If you have not spent time looking at the latest release of the Metashape Viewer, then I would urge you do so.

Its gone beyond a simple viewer and contains a rich set of tools for sharing and analysing 3D content...more details here:

One of our clients will be adopting it for sharing data amongst their user base.

Its a free product and with the latest release very much something Agisoft should be proud of.

General / Re: Processing a massive underwater photoset without GPS
« on: October 29, 2021, 11:43:02 AM »
Sequential would not like my mixing of tracks I guess

Mine neither. But that is not the reason I do not use it.

To reiterate
Quote will not match adjacent images in parallel runs
is the reason.

Sequential works well with planned mission drone flights. We divers are not drones. Its not going to fix your issue, but if you want to try it then I believe its based on the EXIF image creation time, not filename or folder structure.

Each camera image should align to its neighbour. But no alignment will occur between the camera image sets using sequential. A second alignment will be needed with Reset Alignment ticked off to align all points.

And to reiterate:

Unless the GPS data is accurate then adding it won't help.

If you really want to go the accurate underwater GPS route then its possible. A budget minimum of perhaps $70~100k would see the issue fixed, but it will still come with limitations, setup and working methodology that would add time to the work on site.

Remember, everything can be fixed...but it all comes with cost.

If you have not used video then don''t bother - stills will deliver more data for less work.

You may be generating more images and therefore more data than is required to produce a result. The entire Thistlegorm - 7 acres - took 24,000 DSLR images (see More images is not always best...its the correct number we really need.

Shooting at 3 to 4m from the subject should provide massive coverage...thats far too distant for my style which is typically 1~2m to allow the strobe light to restore gut feeling is there are more images than really needed in the project.

There is no magic silver plated solution here.

There is a mass of data to work through, You could spend more on processing hardware, change the cameras...but the basic approach of how the images are captured might be the best place to start - and its zero cost beyond the time needed.

General / Re: Processing a massive underwater photoset without GPS
« on: October 28, 2021, 06:53:10 PM »
Unless the GPS data is accurate then adding it won't help.

Test this by shooting a dataset with an iPhone...then use Reference Preselection set to source and watch what happens.

Last time I tested it, a mess as the embedded GPS values were good enough to tell me roughly in the world where the image was shot...and inaccurate enough to confuse Metashape.

We do work with underwater GPS and merge the camera positions into the JPEG data...but its never used for preselection. We have gone as far as writing a tool to merge GPS data with images - thats how useful it can be - but not for preselection. See for more details.

Sequential might work if you are very disciplined with the sequence of image creation, but it will not match adjacent images in parallel runs. Again, for good reasons we don't use this underwater.

So what to do?

First step is to look at the process of gathering images - are you shooting stills? Or deriving still images from video?

This is a fundamental question. Video is popular underwater, but it carries a whole set of issues still images simply do not generate.

So its worth understanding that before going further - what method do you use?

Pages: [1] 2 3 4