Trimensional: 3D Scanner for iPhone • Hacker News Board

Re: Trimensional: 3D Scanner for iPhone

#31

Post by anoved » Thu, Jan 06, 2011, 9:00 PM UTC

dy wrote: post #23

motters wrote: post #12

This is a shape from shading approach, which will only work if you're in the dark, with the phone as the only illumination source. If white dots are shown in different places on the screen, and assuming the phone and subject don't move during the process, surface normals can be computed from the resulting images, and once you have the normals then the shape can be approximated. Normals can be found by calculating the…

What are good resources for looking into converting photos into 3d object models? I'm really impressed by Shapeways but would like to take current real-world objects as a base rather than building them in a 3D tool etc. I've seen the laser scanners but they're relatively expensive. Is there anything like a mount that takes two iphones, and software that can take those two photos to create atleast a projection?

If you're working with real-world objects, one approach is to place the object of interest on a turntable, allowing you to capture multiple perspectives with a single camera/sensor. Philo Hurbain has made some delightfully clever LEGO NXT 3D scanners this way (delightful especially because they're used, in turn, to digitize the shape of complex LEGO parts) - one using a needle probe, and another using a laser.

http://philohome.com/scan3d/scan3d.htm http://philohome.com/scan3dlaser/scan3dlaser.htm

You might also be interested in the Makerbot folks' structured light 3d scanner kit: http://blog.makerbot.com/2010/09/14/new-makerbot-3d-scanner-...

Re: Trimensional: 3D Scanner for iPhone

#32

Post by gridspy » Thu, Jan 06, 2011, 9:45 PM UTC

sbierwagen wrote: post #20

ericb wrote: post #9

The fact that this only works in the dark made me wonder, how much of what the Kinect does could be possible on an iPhone, and what would be needed to get there? 2 Cameras? What else?

If your subject doesn't move, two cameras can be approximated by taking two pictures a set distance apart.[1] Also note that the method used by this app is very short ranged, and uses the LCD's backlight while it's imaging, so there's zero feedback, making any kind of interactive application impossible. 1: There are third party accessories to make this easy and repeatable, built with varying levels of quality. Here's…

You could interleave the illumination of the subject with each photo taken

1. Illuminate 2. Take photo 3. Show photo

Repeat.

If step 2 is really short, you could have the illumination phase be much shorter than the show photo phase and the user of the phone would see it as 4 short flashes over their own photo.

Re: Trimensional: 3D Scanner for iPhone

#33

Post by vilya » Thu, Jan 06, 2011, 10:05 PM UTC

dy wrote: post #23

motters wrote: post #12

This is a shape from shading approach, which will only work if you're in the dark, with the phone as the only illumination source. If white dots are shown in different places on the screen, and assuming the phone and subject don't move during the process, surface normals can be computed from the resulting images, and once you have the normals then the shape can be approximated. Normals can be found by calculating the…

What are good resources for looking into converting photos into 3d object models? I'm really impressed by Shapeways but would like to take current real-world objects as a base rather than building them in a 3D tool etc. I've seen the laser scanners but they're relatively expensive. Is there anything like a mount that takes two iphones, and software that can take those two photos to create atleast a projection?

There's an ongoing effort to add 3D reconstruction into the OpenCV library: http://opencv.willowgarage.com/wiki/EffortFor3dReconstructio...

If you're not already familiar with OpenCV, it's a rather good (and well documented!) open source image processing library. It's written in C++ but has bindings for a bunch of other languages too.

Re: Trimensional: 3D Scanner for iPhone

#34

Post by lwat » Thu, Jan 06, 2011, 10:38 PM UTC

dy wrote: post #23

motters wrote: post #12

This is a shape from shading approach, which will only work if you're in the dark, with the phone as the only illumination source. If white dots are shown in different places on the screen, and assuming the phone and subject don't move during the process, surface normals can be computed from the resulting images, and once you have the normals then the shape can be approximated. Normals can be found by calculating the…

What are good resources for looking into converting photos into 3d object models? I'm really impressed by Shapeways but would like to take current real-world objects as a base rather than building them in a 3D tool etc. I've seen the laser scanners but they're relatively expensive. Is there anything like a mount that takes two iphones, and software that can take those two photos to create atleast a projection?

Shapeways should run a service when you send them a part or two and they scan it to turn it into a 3D model ready to modify and print.

Re: Trimensional: 3D Scanner for iPhone

#35

Post by antirez » Fri, Jan 07, 2011, 12:26 AM UTC

zach wrote: post #30

antirez wrote: post #25

Very cool and very uncool. Cool: that it works in a decent way, and uses a neat trick. Uncool: You can't export the image into a 3D file, making it 99% less useful that it would be otherwise. Suggestion: export it as VRML, it's trivial format that you can generate starting from your points. Use this format (from my own code, so use it as you wish): fprintf(fp, "#VRML V2.0 utf8\n" "Shape {\n" " appearance Appearance {…

Wow, there's been a VRML sighting! As an old dude, VRML reminds me of the worst of 90s web hype. Trying to leave that aside, I also don't think it has a lot going for it to keep it around as a format. I prefer the even simpler Wavefront OBJ format as a scratch format. It's about as printf-compatible as it gets and is supported in many more places than VRML. http://en.wikipedia.org/wiki/Wavefront_.obj_file

Good point, but unfortunately in wavefront .obj there is no "elevation mesh" alike object, so it's a bit more complex than this, but still not too hard.

Btw while VRML as a plugin and the idea of a 3D web sounds now 90s, the data format itself is too bad.

Re: Trimensional: 3D Scanner for iPhone

#36

Post by greendestiny » Fri, Jan 07, 2011, 12:50 AM UTC

dy wrote: post #23

motters wrote: post #12

This is a shape from shading approach, which will only work if you're in the dark, with the phone as the only illumination source. If white dots are shown in different places on the screen, and assuming the phone and subject don't move during the process, surface normals can be computed from the resulting images, and once you have the normals then the shape can be approximated. Normals can be found by calculating the…

What are good resources for looking into converting photos into 3d object models? I'm really impressed by Shapeways but would like to take current real-world objects as a base rather than building them in a 3D tool etc. I've seen the laser scanners but they're relatively expensive. Is there anything like a mount that takes two iphones, and software that can take those two photos to create atleast a projection?

There are a lot of approaches. Yes there is software that takes two photos and let you reconstruct 3d. If you have a man-made object you probably don't want a generic point-cloud building approach (like say http://www.photosculpt.net/ ) - but rather something like Photomodeler that lets you select vertices and build up surfaces.

There is also software that builds models from silhouette methods, that usually require you printing out targets which you place the model, so of like a manual turntable approach. I can't remember the name of software that does this at the moment, but its out there.

Or you could work from video (just from a single camera) that you move around. That can be effective, not sure of the best software for doing this - it's called structure from motion, a quick google shows some source at this project site: http://phototour.cs.washington.edu/

There some code out there for a do it yourself laser scanner - this isn't what I was thinking of but it seems kind of cool: http://www.youtube.com/watch?v=xK5eYhpBtQc

I've also seen some do it yourself structured light software (ie bring your own projector and camera), that seems to work ok.

It kind of depends on what size and type of objects you want to scan - things like the surface properties could be important - also how long you can keep it still.

Re: Trimensional: 3D Scanner for iPhone

#37

Post by jfeldstein2 » Fri, Jan 07, 2011, 1:59 AM UTC

Can't wait until someone pipes this into a reprap.

Re: Trimensional: 3D Scanner for iPhone

#38

Post by chadaustin » Fri, Jan 07, 2011, 2:21 AM UTC

zach wrote: post #30

antirez wrote: post #25

Very cool and very uncool. Cool: that it works in a decent way, and uses a neat trick. Uncool: You can't export the image into a 3D file, making it 99% less useful that it would be otherwise. Suggestion: export it as VRML, it's trivial format that you can generate starting from your points. Use this format (from my own code, so use it as you wish): fprintf(fp, "#VRML V2.0 utf8\n" "Shape {\n" " appearance Appearance {…

Wow, there's been a VRML sighting! As an old dude, VRML reminds me of the worst of 90s web hype. Trying to leave that aside, I also don't think it has a lot going for it to keep it around as a format. I prefer the even simpler Wavefront OBJ format as a scratch format. It's about as printf-compatible as it gets and is supported in many more places than VRML. http://en.wikipedia.org/wiki/Wavefront_.obj_file

VRML was the interchange format of choice back when I worked on OpenSG at Iowa State. OBJ was too limiting.

Re: Trimensional: 3D Scanner for iPhone

#39

Post by [deleted] » Fri, Jan 07, 2011, 2:21 AM UTC

zach wrote: post #30

antirez wrote: post #25

Very cool and very uncool. Cool: that it works in a decent way, and uses a neat trick. Uncool: You can't export the image into a 3D file, making it 99% less useful that it would be otherwise. Suggestion: export it as VRML, it's trivial format that you can generate starting from your points. Use this format (from my own code, so use it as you wish): fprintf(fp, "#VRML V2.0 utf8\n" "Shape {\n" " appearance Appearance {…

Wow, there's been a VRML sighting! As an old dude, VRML reminds me of the worst of 90s web hype. Trying to leave that aside, I also don't think it has a lot going for it to keep it around as a format. I prefer the even simpler Wavefront OBJ format as a scratch format. It's about as printf-compatible as it gets and is supported in many more places than VRML. http://en.wikipedia.org/wiki/Wavefront_.obj_file

[deleted]

Re: Trimensional: 3D Scanner for iPhone

#40

Post by m_eiman » Fri, Jan 07, 2011, 2:55 AM UTC

anoved wrote: post #29

sbierwagen wrote: post #20

Earlier quoted context omitted.

If your subject doesn't move, two cameras can be approximated by taking two pictures a set distance apart.[1] Also note that the method used by this app is very short ranged, and uses the LCD's backlight while it's imaging, so there's zero feedback, making any kind of interactive application impossible. 1: There are third party accessories to make this easy and repeatable, built with varying levels of quality. Here's…

Or what about using built-in motion sensors to record the relative camera location and orientation of a series of frames captured with an e.g. iPhone camera? I don't know exactly how the accelerometers and gyros work, or what sort of data they provide (linear distance vs just orientation changes?), but imagine holding down a "scan" button as you simply swing the phone around a subject to capture a series of images. I…

Tracking movement in 3D using dead reckoning is apparently very inaccurate, with the iPhone sensors I wouldn't expect it to be accurate for more than a few seconds at best. I visited a startup working on the problem a few years ago, and they had problems even with dedicated hardware.