Messages

31

General / Re: image stabilisation - yes or no

« on: June 15, 2021, 11:03:58 PM »

As mentioned, IS changes the camera model (intrinsic parameters) in a non-reproducible fashion.
HOWEVER, despite this obvious error introduction, what are the "real world" implications?

I'm sometimes confronted with projects, where there is little chance to optimize the image capture process (i.e. using a long monopod without the possibility for additional artificial lighting).
Images with motion blur in such a situation almost certainly introduce more reconstruction errors than IS-images?!

Does anyone know of any scientifically evaluated comparisons (i.e. controlled setup) between IS v.s. non-IS?
My guess is, that IS-images will introduce more noise (assuming oblique image-cature scenarios with solid  projection angles).

Otherwise, this "IS-subject" remains foggy...

32

General / Re: i have question about Roughness and metalic Texture

« on: May 21, 2021, 11:08:04 PM »

Hi,

Metashape "only" extracts the diffuse texture (and optionally normal and occlusion map), so deriving specular and glossiness maps is manual "guess work" (i.e. not physically correct).
There are 3rd party tools for extracting gloss and specular based on the diffuse map, however, the resulting textures are not accurate.

I therefore take a predefined material in the target 3d application which kind of matches the desired characteristics of my photoscanned object as reference for the other maps.
Then it's tedious Photoshopping/masking using the diffuse texture as a basis.

Yes, getting the physically correct specular/gloss (or metal/roughness) maps from photoscanned projects would be awsome!
However, this would require a complex setup with varying illumination angles, colors etc. per shot (search for scanned materials, light field).

If anyone knows of a more efficient approach, I'd also be extremely grateful

33

General / Re: First UAV for archaeological surveying on a budget

« on: November 18, 2020, 03:08:35 PM »

I primarily use the Mavic 2 Pro for cultural heritage projects, mainly building documentation.
But your requirements may differ.

Pros:
- portability of course
- long flight duration (30 min)
- great image quality for a small sensor:
20 MP/ RAW, Camera is produced in cooperation with Hasselblad (but this may be mainly marketing/branding)
- highly reliable obstacle avoidance (for me a _must_ for oblique image projects where one often needs to fly close to the object and/or avoid structural obstacles)
- great stabilization when hovering, as it uses additional ground sensing cameras (allows for long exposures, even indoors without GPS)
- so far I've successfully used it with the flight planning tools DJI GS Pro, Pix4d and Map Pilot. But threre are many more apps, just haven't used them long enough for a substantial judgement

Cons:
- ISO limitations: beyond 200, such sensors produce far too much noise, IMHO

I've also used the Inspire with a Zenmuse X5 (FC550) in parallel to the Mavic 2 Pro on the same project, giving me a rare one-to-one comparison:
the image quality is identical (judged using the RAWs in Lightroom)!

34

General / Re: Can't move object

« on: April 22, 2019, 10:08:05 AM »

Maybe because the model already has a global orientation (i.e. from camera-GPS)?
In this case you can choose "Reset Transform" in the Object Move/Rotate/Scale pulldown menu.

35

General / Re: How high an overlap percentage is too much?

« on: January 15, 2019, 02:34:16 PM »

Hi Brit,

a few things come to mind if you need to reduce processing time for your scene:

• RAM: I always have the Task Manager running when processing scenes. If more than 32 GB are used in your case, processing will take too long
• Region: the Region seems rather large. Check if you can scale it down to just the hill
• Medium vs. High: the performance penalty for High quality is VERY large. Medium should be fine with Mavic 2 images (of course depending on the LOD you require)
• Orbits: I've found that 5 degrees (=72 images) is on the safe side, but I've also had sucessful turntable scans with 10 degrees

36

General / Re: Pc Build Help

« on: December 21, 2018, 06:33:16 PM »

When configuring my workstation I was also considering the TR 2990WX.
However, due to the memory management, the 32 cores don't scale well with all applications, sometimes there is even a performance penalty.

I therefore chose the 16 core 2950X and am absolutely satisfied: it also has great single core performance (useful in many other applications surrounding photogrammetry, i.e. RAW image processing, point cloud editing etc.).

Currently there are also other top CPUs for photogrammetry (such as the i9 9900K), but they don't have the 3d rendering performance of 16 or 32 core TRs and they "only" support 64 GB RAM.

Here's a bench mark overview: https://www.anandtech.com/bench/CPU-2019/2260 (which is based on the older Photoscan 1.3.3 version).

37

General / Re: How to generate a mesh for very thin surface?

« on: December 18, 2018, 03:43:18 PM »

You may want to check this blog entry:
http://www.agisoft.com/index.php?id=48

38

General / Re: ssd evo 970 paging file

« on: December 14, 2018, 08:23:09 PM »

Just for a comparison of the sequential read spead:
SSD: 3560 MB/s (my 970 evo NVMe)
RAM: 64575 MB/sec (at 2900 MHz)

So no, you'll never ever want to get into swap space (however fast your SSD), it brings the processing nearly to a halt (the processor cores are just not receiving enough data).

You may also want to check if "very high quality" is actually necessary for your anticipated output?!
Processing time increases exponentially between the various quality settings, and so does the amount of output data (with issues maybe in handling such large data in further steps?).