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Thomas M.
03-19-2009, 08:46 AM
Does anybody know of articles or tutorials on how to capture real life set data for easy 3d reconstruction? After the last disaster in the field I plan to buy a Laser distance measuring device up to 150m. But this alone is not a good solution. So I need to gain some expertise too to do the next job painless. I wondered if shooting stereoscopic images does help in any way or filming the set (subway station) with a HD video cam does help if I'd buy syntheyes or something similar.

Any links? Any advice?

Cheers
Thomas

Thomas M.
03-19-2009, 09:37 AM
P.S.: The setup is for a still image.

Wopmay
03-19-2009, 11:35 AM
Does anybody know of articles or tutorials on how to capture real life set data for easy 3d reconstruction? After the last disaster in the field I plan to buy a Laser distance measuring device up to 150m. But this alone is not a good solution. So I need to gain some expertise too to do the next job painless. I wondered if shooting stereoscopic images does help in any way or filming the set (subway station) with a HD video cam does help if I'd buy syntheyes or something similar.

Any links? Any advice?

Cheers
Thomas


Is Image Modeler what you need? It reverse engineers geometry from ordinary still photos. Works pretty well once you get past the funky user interface. The word "easy" being open for discussion. Recently acquired by Autodesk from the French company RealViz.

http://usa.autodesk.com/adsk/servlet/index?id=11390028&siteID=123112

biliousfrog
03-19-2009, 11:45 AM
If you just want some reference points in order to rebuild it in 3d then moving around the set with an HD camera and using a matchmoving app would give you those reference points. It's not an easy thing to do but it is possible.

As it's only for a still image, I'd just eyeball it and get any measurements that you need on set.

Is it a set extension or something?

Thomas M.
03-19-2009, 12:28 PM
I need to wrap up the whole set, so eyeballing is no option. I need something precise. My experience from last time is that a 1cm mismatch is too much. I do hope that the floor is even, so that all object do have the same ground level. But in general the last method to measure the distance to the object is a good point. I just wondered if two exposures (left eye/right eye would be of any help.

Which software would I need to reconstruct the environment with a HD video cam? I guess the lens distortion will be a problem.

Image modeler 4 is still one of the softwares in my arsenal. I used it, but it's not a great program. Canoma for the Mac was great, but Adobe bought it and it disappeared. You could reconstruct everything from a single photo, much better than Image modeler.

But in general, aren't there any tutorials out the describing different methods to do this?

biliousfrog
03-19-2009, 02:48 PM
But in general, aren't there any tutorials out the describing different methods to do this?

http://www.thegnomonworkshop.com/store/category/23/Digital-Sets

Wopmay
03-19-2009, 03:09 PM
I do hope that the floor is even, so that all object do have the same ground level.

Yea. Be careful of this. I once had a horrible time with Image Modeler until we realized the floor was not level. It was really screwing everything up. After that was discovered, Image Modeler worked "okay" but we were able to eyeball a lot of it.

If you need super accuracy, you might want a LIDAR system. I imagine it would be a lot of work to clean it up, though. Again, "a lot of work" being open to interpretation.

Thomas M.
03-19-2009, 04:07 PM
How much is a LIDAR system? I guess it's 40.000+

Titus
03-19-2009, 04:42 PM
Does anybody know of articles or tutorials on how to capture real life set data for easy 3d reconstruction? After the last disaster in the field I plan to buy a Laser distance measuring device up to 150m. But this alone is not a good solution. So I need to gain some expertise too to do the next job painless. I wondered if shooting stereoscopic images does help in any way or filming the set (subway station) with a HD video cam does help if I'd buy syntheyes or something similar.

Any links? Any advice?

Cheers
Thomas

Camera tracking software is helpful to reconstruct part of the scene, using the tracking points as reference.

Thomas M.
03-19-2009, 04:57 PM
I just wonder if I'd buy Syntheyes, if I'll be able to generate those marks with 3,4,5 still images shot from different locations on a tripod or if I do need to shoot a small film. On their webpage I found a tutorial for one photo, but it doesn't generate any depth information of course. Anybody a guess?

lwanmtr
03-19-2009, 05:05 PM
Lidar produces good accuracy, but you will still have to model the objects yourself, using the lidar generated model as a guide.

Titus
03-19-2009, 06:14 PM
I just wonder if I'd buy Syntheyes, if I'll be able to generate those marks with 3,4,5 still images shot from different locations on a tripod or if I do need to shoot a small film. On their webpage I found a tutorial for one photo, but it doesn't generate any depth information of course. Anybody a guess?

You better shoot a video. I've made a lot of trackings with boujou and voodoo, the most impressive was the video of a plane, and the markings I got were very accurate even the scale was 1:1.

Thomas M.
03-19-2009, 06:45 PM
Mmmh, I guess the tracking software can work great. My problem is to recreate a set, so I need to know the distances to the object so that I can place geometry in those places resembling the architecture on location. Due to the size of the location I won't be able to measure sizes directly (heigth of a column, length of a wall, etc). So I need a software which spits out tracking points or simple geometry which resembles the the location 1:1. Generating the tracking points with a video camera might be a solution, but I'd say the resolution is too low. So it'll be a series of shots with a 12 or 24 MP camera. I wonder how may shots I need to pull this off.

P.S.: ImageModeler is rather dull!

Wopmay
03-19-2009, 08:06 PM
How much is a LIDAR system? I guess it's 40.000+

I think if the budget allows it, you'd want to find somebody to come out and do it for you. (Or is that what you meant?) Either way, I don't know about cost. I had a card from a guy who does it but I can't find it. You can probably find it through the Visual Effects Society or something.

radams
03-19-2009, 10:02 PM
Hi All,

Well, what are you looking to do with the Data ?

What are you trying to do with LW and this set ?

There are many ways to approach this....some time consuming...some expensive.

What is your time line, budget, and results desired or needed ?

Cheers,

Thomas M.
03-20-2009, 01:03 AM
I need to recreate a metro station (underground). Point is that the station needs to match up perfectly with a photo I will take. So accuracy is an issue. Budget will be pretty low, so I guess lidar is out of question. I do hope that the station consists mainly out of geometric shapes. My worst fear is that the platforms will be bend and I don't have straight line.

I guess a mixture out of taking distance measurements, placing reference marks on the ground with defined distances and taking stereo images/image series (image modeler) should deliver a solution.

I don't want point clouds or anything like this. I'm looking more for ways to determine where exactly to place a cube, a column, etc. So markers would be a cool thing.

Thomas M.
03-20-2009, 01:29 AM
Well, both Worley plug ins assume that you already have a correct model. It's to align background and model.

In my case I don't have a model, that's what I need to create from my survey data.

But thanks for the tip.

Thomas M.
03-20-2009, 06:58 AM
Just bought Syntheyes. Need to try it next week and check what it is able to pull off the hat. Hopefully it works with shooting image series with my old Nikon D70. Don't want to buy a crappy HD cam.

Anybody any experience with HD cams? 1000 +/-? Probably - 1500?

Thomas M.
03-21-2009, 03:16 AM
Thanks Megalodon. Taft is great if you have a model and a reference image. Without the model it's useless. As I will be on a location I need to capture data, that enables me to build a model. Therefore I need data like distances, size, etc. If there's a column in my photo, I won't know how far it is away from the camera and neither its width or height. But my brain knows the general shape, it's round. If I know the perspective, camera heigth and angle towards the objects, I could move a cylinder towards the column position in layout till it matches up with the background photo. If I measured the distance of the column I could easily scale x and z axis till it fits.

Or another example: If I would get the corner points from a room from Syntheyes. I could recreate the room pretty easily. Other reference markers would tell me the position of the carpet corners or the legs from a table. If I took measurements of the table and other objects. It would be pretty easy to place those objects in my scene.

I hope Syntheyes is what I'm looking for. I even thought that it might be great to model a car. Spill some amounts of confetti on the car (e.g. the hood), track it, generate a point cloud or simple polymesh and you sould get a great idea about the shape and curvature. You could the model with splines or something else to replace the approximation of the form.

radams
03-21-2009, 01:02 PM
Hi Thomas,

I'ld like to give you a hand...it really does depend on what you are wanting to do with this data & Set...to help you work out the best solution to your, budget, time and needs.

I could write a book or two...on how to approach this...but I really need to know what you are needing.

Before a lot of these new digitizing devices....& apps...
Measuring tape, wire or twine, levels, protractors, etc...
Along with lots of photos and markers...with lighting balls, etc...

I would still recommend..using a GOOD still camera with a GOOD lens...and to pre shoot a registraion chart...and set up the lens distortion...to correct for it....

Cheers,

Thomas M.
03-22-2009, 04:01 AM
Just fooled around with Syntheyes yesterday for half an hour and I need to say it's interesting. I just need to find a small subject where I can check how good it is to create point markers which could then determine the border or corner of a simple object like a cube. I just need to figure out how to set up a scale for the scene to have absolut measurements afterwards.

archijam
03-22-2009, 05:53 AM
With syntheyes, perhaps you can use ssonntech's own basic tutorials to plan a few separate pans or tripod work:

http://www.ssontech.com/pathology.htm

The accuracy with which you can place the lens of your camera over your pivot point will GREATLY effect the accuracy of the marker data that you collect.