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Messages - Marcel

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76
General / Re: Calibration/Accuracy possible with Photoscan?
« on: March 08, 2015, 11:05:17 PM »
What size are the objects you want to scan?

If you can photograph it with enough resolution, then Photoscan can build it. But it all depends on the size of  the object.


77
General / Re: Best practices for tank scanning
« on: March 07, 2015, 10:42:14 PM »
I strongly advise to get a tripod (and a remote release cable). For good quality photos you need to use a low ISO, and you cannot handheld photos at those shutterspeeds.

78
General / Re: Best practices for tank scanning
« on: March 07, 2015, 01:06:07 PM »
The "Airstream" trailer is not an ideal test subject. It has lots of reflections, and hardly any usable surface detail for Photoscan to determine the surface shape. Apart from the seams and rivets, it's all flat and smooth. Try finding something that is dirty and old, like a statue or a really old and dirty car.


Your photos have a lot of noise because your camera was at ISO2200. For better results the photos need to be as noise free as possible.

To improve the quality of your photos:

- put your camera on a tripod
- use a low ISO (ISO100)
- camera in A (Aperture) mode with the Aperture between F8 and F11
- use a remote release cord (so you don't move the camera while pressing the shutter button)
- when you convert from NEF to JPG, save at the highest possible setting (JPG Quality 12 in Photoshop).

Using JPGs is fine, but you have to save them with the highest possible quality to prevent compression artefacts.

Your photos are all more or less at eye height, with the camera pointing down for parts of the trailer that are low to the ground. Using multiple rows of photos will give better results (high, medium, low). So put your tripod at the highest position for the top row, at medium position for the middle row, and at very lowest for the bottom row. That way the camera position changes, which will make it easier for Photoscan to do an accurate reconstruction.


79
General / Re: Tie points once again
« on: March 07, 2015, 12:38:49 AM »
I think in one of the posts it is stated that tie point config automatically filters out "badly" projected points

That is actually an interesting idea. Perhaps Alexey could confirm this? When the Tie point setting is active, does Photoscan rate the quality of the points and use only the highest quality points?

Personally I set it to 0. The alignment never takes a very long time anyway  (compared to the Dense Cloud reconstruction). I rather have it run for an hour and be sure that it has the best alignment possible.

80
General / Re: 1080p and 4K Video --> Point Cloud --> Mesh
« on: March 06, 2015, 11:58:11 AM »
Awesome idea using Google Earth as source images :)


I am wondering if it makes sense to use every frame of the video? The camera positions will be very close to each other, so the amount of information Photoscan can extract is low. (With regular photos, if cameras are close together it can lead to bad alignments and noise in the scan)

81
General / Re: Best practices for tank scanning
« on: March 06, 2015, 11:54:03 AM »
What kind of tank? One with a cannon on top or an oil storage tank?

Use a tripod and make well exposed and sharp images. Sound simple right :)

Show us the results, I am very curious how it turns out!

82
General / Re: Not Enough memory
« on: March 05, 2015, 11:29:43 AM »
That depends on the number of photos in your project, and the size of your images. So give us a bit more info?


83
General / Re: Error "Align Photos"
« on: March 04, 2015, 12:43:30 PM »
Can you show us some example images at full resolution?

Quote
zoom in does not work well

If you use Orthographic mode (press '5') you will be able to zoom in much closer to your point cloud.

84
General / Re: Canon EOS 5DS R 50MP
« on: March 04, 2015, 12:40:29 PM »
Wishgranter hits the nail on the head. 50MP is great, but not many lenses will be able to resolve that amount of detail.

And unless you are planning to  process  your Dense Cloud at 'Ultra' then it doesn't make sense to invest in a 50MP camera anyway. For most users it will be better to invest in a good lens and do everything to improve the image quality.

85
General / Re: Sony a7r triggering
« on: March 02, 2015, 03:19:34 PM »
It has also a input slot on the side, which looks like usb but is a better one (sony) with additional ports.

'proprietary' is the word, not better.

I find it plain annoying. With my other cameras I can just cut the cord off a 5$ remote and solder on some switch or triggering device, but for the Sony you cannot do that because of it's special Multi port. So you are stuck with the default Sony remote release (which you cannot even hack because it's full of electronics as well) or buy the above converter cable for 89$.

Edit: you are in luck, it seems there are much cheaper options available now:

http://www.ebay.com/itm/231256005313?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

86
General / Re: Sony a7r triggering
« on: March 02, 2015, 01:37:48 PM »
Not completely related to your question, but I do have a trigger cable for the Sony A7R that allows you to hook up a regular remote (ie. a simple switch you might be able to trigger in some other way). It's this cable:

http://gethypoxic.com/collections/camera-switches-and-adapters/products/sony-multi-terminal-to-2-5mm-shutter-release-adapter

I'm not using it anymore, so you can buy it from me for cheap. If you are interested send me a PM or email.

87
General / Re: Ripple / staircase artifacts on 3D reconstruction
« on: March 02, 2015, 01:30:05 PM »
We've had 'staircasing' artifacts as well (we nicked it "stepping"), but it was usually just small that were raised a bit higher than the rest of the scan.

Our interpretation was that it had to do with an incorrect alignment of the cameras as well (ie. a camera pair that had an incorrect position but still contributed to the Dense Cloud).

Now we manually go through the cameras after alignment, and remove any cameras that are too close to each other. We also cull the sparse cloud and then run Optimize Cameras. That (and better quality images) seemed to have gotten rid of it.

88
General / Re: Camera station questions
« on: February 26, 2015, 12:25:53 PM »
What do you mean with Parallax changes? Parallax as in the 'no parallax point' for panoramas?

I was using a 2 camera setup (2x Sony A7R) and I was running into a lot of trouble with shutter shock. The shutters never trigger exactly at the same time, so in a lot of photos there was subtle motion blur because of the shutter shock from the other camera. The effect was very subtle, but enough to cause noise in the scans.

So when using multiple cameras I would certainly use a camera that supports EFC to minimize shutter shock, and a very sturdy pole.

89
General / Re: GPU memory inconsistency and CPU questions...
« on: February 25, 2015, 08:58:41 PM »
GPU load is in spurts, that is correct. Also note that Photoscan uses only a specific part of the GPU, for this reason you might not see 100% load either.

The CPU cores option applies only to the Dense Cloud stage (because that is the only stage where the GPU is used). Other stages (Alignment, Meshing, Texture building) use all available processing power because they are CPU only.

I've got it set to use zero cores, because the CPU doesn't do much anyway. Also, when it's set to zero cores I can start a second Dense Cloud reconstruction as soon as the first enters the "Depth Map FIltering" stage. So you can overlap processing of two projects without much slowdown.

90
General / Re: Decreasing Dense Point Cloud Rendering Time
« on: February 23, 2015, 11:33:29 PM »
More than 2 GPU's is really not worth it. This is in big part because the Dense Cloud reconstruction phase is only about 50% GPU accelerated. The other half (depth map filtering) is runs completely on the CPU. So going from 2 to 4 GPU only makes the processing 40% faster.

(This is apart from the fact that you would need a very big power supply, it's hard to fit more than 2 GPUs in a case, and you'll probably run into heat problems).

I can't tell exactly if the single or dual setup will be faster (and it is also a matter of cost vs performance). Our experience is that the fast single CPU system is faster, but we are not using the exact same CPUs as in your example.

Unless you are absolutely sure that you have a ton of Photoscan work coming up, I would start with a decent but not ridicilously overspecced machine. You can always buy a second computer later on when you know exactly what you need (and have it dedicated to processing).

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