Multi-camera setup project.

mphx

210

Re: Multi-camera setup project.

« Reply #300 on: 21 / January / 2015, 05:04:09 »

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Quote from: andrew.stephens.754365 on 20 / January / 2015, 18:08:49

would, sometime, like to hear test results/comment for a tailors dummy (static object) with:
(i) half camera count in continuous light&no projection (texture)
(ii) half camera count in continuous light & projection (geometry)

insofar as time saving is concerned (or lack of - in post processing).

The test , in fact , was two shootings , one with projection on and one with projection off , to compare results.
With projection on , results were better (naturally) but the real question is .. is it worth the trouble/buying the projectors?
Answer depends on the person being shot , how much skin is uncovered (hands , feet , etc) , what kind of clothes he/she wears and stuff like that.

There will be few cases that projection will help ALOT and some other cases (most of them) that projection will help A LITTLE.
In any case will save us minimum 1-2 hours of manual work.So in general , it worths the trouble..as far as we can find some money to buy them , since they are not that cheap

So ... todo list => find money for 3 projectors

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andrew.stephens.754365

461

Re: Multi-camera setup project.

« Reply #301 on: 21 / January / 2015, 07:25:04 »

Very informative mphx. Thanks.

Quote from: mphx on 21 / January / 2015, 05:04:09

The test , in fact , was two shootings , one with projection on and one with projection off , to compare results.

Was the camera count split between the two shootings (or full for both)?

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mphx

210

Re: Multi-camera setup project.

« Reply #302 on: 21 / January / 2015, 10:21:37 »

Quote from: andrew.stephens.754365 on 21 / January / 2015, 07:25:04

Very informative mphx. Thanks.

Was the camera count split between the two shootings (or full for both)?

Full for both.

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andrew.stephens.754365

461

Re: Multi-camera setup project.

« Reply #303 on: 04 / August / 2015, 05:38:00 »

Quote from: mphx on 28 / November / 2014, 16:20:31

PS: Things are a bit better with dng format (raw format) because we can mass manipulate photos in photoshop and remove noise BUT jpeg photo is like ~4mb and dng photo is like ~20mb.
Transferring photos from cameras to pc take ages with dng..not very practical...so we are sticking to jpeg for the time being..since the job is done with them...

Some further related & interesting comment:

http://www.agisoft.com/forum/index.php?topic=1378.msg20787#msg20787

Quote from: bigben

Quote from: chadfx

If I am using CDHK with a Canon compact camera (A3300 IS) and shoot in DNG raw, it does not automatically correct for the lens distortion...so it appears different from the JPGs coming out of the camera. ...

On this part of the original question... I wouldn't do any distortion correction prior to using Photoscan as you can either provide calibrated values to Photoscan or have it calculate distortion parameters for you. If the image offset calculated by Photoscan is different to that used in the in-camera correction then you will effectively be using distorted images.

http://www.agisoft.com/forum/index.php?topic=1378.msg20814#msg20814

Quote from: chadfx

That makes sense, thanks. I know that outside perspective correction is a usually a strict no-no for Photoscan. It sounds like it will figure it all out on its own either way (camera corrected JPGs or uncorrected RAWs). I certainly haven't had poor results from the RAWs, but it would be worth a comparison at some point I suppose (if only time were more plentiful...sigh)

http://www.agisoft.com/forum/index.php?topic=1378.msg20816#msg20816

Quote from: bigben

Photoscan will figure "something" out regardless but not neces4444444sarily "it"... eg. you can feed it fisheye images and process them as rectilinear and it will figure something out. The calculations for lens distortion are all done from the optical centre of the image. If you in-camera correction does this on the geometric centre of the image file and the optical centre of the image is in a different position to this then the final result will be technically distorted, resulting in a mathematical best fit of all of the criteria put together. As a result, camera positions and rotations will also have small errors, compensating for the incorrect distortion correction and you'll see more noise in the sparse point cloud.

If you want a comparison, try creating unfiltered dense clouds.

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mphx

210

Re: Multi-camera setup project.

« Reply #304 on: 18 / September / 2015, 05:31:47 »

@reyalp

Hey , after a long time

Need to ask you something about chdkptp.

We tried the testshot command , in order to see how it behaves because we will need multiple shots in a project we are working.
I tried it with only one camera connected (i remind i am using canon A2500).I set it up to take 2 photos.
It worked well , but there was a pause between of the two shots of around 5 secs.

For the project we want shorter pause , let's say around 2 secs max. Is this hardware related ? or it can be configured in chdkptp ?

Thanks.

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reyalp

14003

Re: Multi-camera setup project.

« Reply #305 on: 18 / September / 2015, 16:35:41 »

Quote from: mphx on 18 / September / 2015, 05:31:47

I tried it with only one camera connected (i remind i am using canon A2500).I set it up to take 2 photos.
It worked well , but there was a pause between of the two shots of around 5 secs.

For the project we want shorter pause , let's say around 2 secs max. Is this hardware related ? or it can be configured in chdkptp ?

testshots was not made fore speed. It does a full half shoot, wait for camera to focus and measure exposure, shoot cycle. It also prints to the screen for 1/2 second and sleeps for another 1/2 second after that.

So you should be able to do a lot better, especially if you want the same exposure and focus for each shot.

A couple possible approaches:
1) Do something like testshots, but put the preshoot outside of the main loop, and modify the shoot commands to use shoot_full_only instead of shoot full. This is probably the simplest code wise, but will slow down with large numbers of cameras, because each shot still requires enough time to trigger all the cameras. Clicking shoot_full_only repeatedly is also slower than true continuous mode on some cameras.

2) Add a camera side function that shoots multiple shots at a given interval, syncing the start and then using the interval to keep sync. This should allow shooting about as fast as a single camera can maintain a steady interval.

I'll see I can come up with code for one or both of these over the weekend.

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mphx

210

Re: Multi-camera setup project.

« Reply #306 on: 18 / September / 2015, 17:28:36 »

@reyalp

We did a test with testshots with all the cameras (64 in number) and the delay was huge...we are talking about like 15secs between the two shots.

I've checked the structure of "testshots" in multicam.lua and i see it uses preshoot + shoot for the shots.
Its logic but at the same time , every preshoot..takes time..plus everything else that the command itself does that take their own time.

We did some manual shooting.. preshoot + shoot...1st shot , plain shoot...2nd shot...2nd shot was messy...so as i said its logic that preshoot is needed before every shot.But it consumes time...

The project we are trying to implement is simple.We need to take two shots in very few secs.. 2-3..5 max.

So we need something that will do the preshoot/set focus/exposure whatever (on one button all of these lets say)...and in a second button a command that takes two shots..as fast as its possible.Something like this..if its possible.

I am trying to figure out what do you mean exactly with the (1) approach..You mean i will make a new command in multicam.lua ?A variation of testshots?Something like this?And put the preshoot thing out of the main loop of this command ?
I remind again , that triggering 64 cameras needs like ~2 secs , secs starting adding up fast...

Its a project we need it done in like 2 months (if we can't manage it no big deal , but it will help us alot in our work)..so take your time

« Last Edit: 18 / September / 2015, 17:31:18 by mphx »

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reyalp

14003

Re: Multi-camera setup project.

« Reply #307 on: 18 / September / 2015, 21:07:42 »

Quote from: mphx on 18 / September / 2015, 17:28:36

We did some manual shooting.. preshoot + shoot...1st shot , plain shoot...2nd shot...2nd shot was messy...so as i said its logic that preshoot is needed before every shot.But it consumes time...

You need to us continuous mode, or keep shoot_half held down between the shots.

Quote

I am trying to figure out what do you mean exactly with the (1) approach..You mean i will make a new command in multicam.lua ?A variation of testshots?Something like this?And put the preshoot thing out of the main loop of this command ?

You would need a variation of testshots, but also new camera side code like shoot or shoot_hook_sync, because the current versions of these do release('shoot_full') which also releases half shoot.

Quote

Its a project we need it done in like 2 months (if we can't manage it no big deal , but it will help us alot in our work)..so take your time

I think this will be fairly simple, and a shooting function more optimized for real use than testshots would be good.

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mphx

210

Re: Multi-camera setup project.

« Reply #308 on: 19 / September / 2015, 08:03:39 »

@reyalp

ok lets see what i understand.

I was reading here http://chdk.wikia.com/wiki/CHDK_scripting#shoot

and i understand that.

1.shoot_half must be issued and held.
2.use shoot_full_only so it will go back to shoot_half and not go to off position.

So what you are saying is , that shoot_hook_sync that i am using (or even the simple shoot) , issues shoot_full and not shoot_full_only that will do the trick.
So it needs some change in the structure of these commands , am i getting it right ?

PS : By the way whats the difference of shoot_half and preshoot i am using ?

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reyalp

14003

Re: Multi-camera setup project.

« Reply #309 on: 19 / September / 2015, 14:07:13 »

Quote from: mphx on 19 / September / 2015, 08:03:39

1.shoot_half must be issued and held.
2.use shoot_full_only so it will go back to shoot_half and not go to off position.

right

Quote

So what you are saying is , that shoot_hook_sync that i am using (or even the simple shoot) , issues shoot_full and not shoot_full_only that will do the trick.
So it needs some change in the structure of these commands , am i getting it right ?

Yes, although I was looking at the code last night and there are some other complications, so it's not quite as simple as just replacing shoot_full with shoot_full_only.

Quote

PS : By the way whats the difference of shoot_half and preshoot i am using ?

What you send with mc:cmd or mc:cmdwait are messages to the camera side multicam script. The script reads these messages and uses them call functions in the cmds table. When you send "preshoot" it calls cmds.preshoot, which presses the shoot_half button, waits for get_shooting() to become true (meaning the focus, auto exposure etc has finished) or time out, and the returns a status.

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