Messages

196

General / Re: Capturing a Coin and Merging Chunks

« on: July 11, 2013, 08:44:55 PM »

Thanks TinCan, so just to be clear...

If I capture sufficiently high detail (more photos, focus stacking, etc) and use a clamp to hold the object in two different positions for two series of photos of the object; then PS should be able to align everything in one chunk?

How do I get rid of the two sections of the clamp to reveal the clean object underneath?

197

General / Re: Capturing a Coin and Merging Chunks

« on: July 11, 2013, 03:33:53 AM »

Just to say that it was "captured by the width of a human hair" seems to beg for it to be attempted, no? ;-)
I applaud your creativity...although for a lot of objects, the notion of super glue would not bode well

My wife thought about trying to suspend it in mid air with magnets in a repel orientation, but I think that would depend on what material the coin was composed of and difficult to keep stable.

Definitely some sort of 'minimal contact' setup would be great...it just needs to be relatively stable as well and hopefully not interfere with any lighting setup.

198

General / Re: Capturing a Coin and Merging Chunks

« on: July 11, 2013, 02:08:08 AM »

Yeah, uniformity and PS do not mix well. ;-)

Thanks Joe, good tips all around. I was essentially attempting this idea (rotate coin in clip for 2nd chunk), but couldn't get the align and merge to work. I was hoping to delete the pieces where the clips are and just merge the 'clean' sections. Wouldn't that be handy? No additional geom or texture cleanup needed! Ah well, maybe it just isn't possible.

Actually, I wonder if keeping the clay helpers in the same positions for both chunks would help with the auto align? But I'd still be left with reconstructing the clay covered bits.

Have you tried using colored clay instead of varying the pattern/sizes? Maybe it's time to hit the art supply store and get some Sculpey.

Cheers, -Chad

199

General / Re: Capturing a Coin and Merging Chunks

« on: July 11, 2013, 12:33:39 AM »

Thanks Joe, that's a pretty clever trick...sort of like adding 'training wheels' to it. I'm hoping to avoid the cleanup stage, but maybe that's just something I'll have to resign myself to.

Are you then capturing each side laying flat down and merging the two sides? Or are you shooting with it propped up and just using the extensions to aid in the alignment/solve?

I was able to merge two flat chunks in Meshlab, as they have an alignment feature between to objects loaded as layers...but when I tried to merge the two aligned layers, the textures broke.

Cheers, -Chad

200

General / Re: Capturing a Coin and Merging Chunks

« on: July 11, 2013, 12:01:04 AM »

Thanks for the suggestion, Wishgranter. I have been able to do the shoot around technique if I lay the coin flat on a surface. I'm not sure if I am understanding how your newspaper trick would help to capture both sides of the coin to become one final object.

Here's a rough example of a coin captured vertically by using some small holding clip at the bottom. But I want to somehow get that bottom part as well, even if I have to merge it in as a separate chunk...I just can't seem to be able to get it to work.
 
http://sketchfab.com/show/fx7oUjg223LW6SQ3ixY9T6Wb34X

If I shoot both sides 'flat' against a surface, I can get each side to build correctly. But PS cannot find enough common points to align/merge the chunks, and the cameras from both chunks are in the same orientation after the align...so I don't think they can help with the aligning of the two chunks.

201

General / Capturing a Coin and Merging Chunks

« on: July 10, 2013, 09:35:13 PM »

Hello again,

I'm trying to find an elegant way to capture a small coin, and have yet to find a reliable method that allows me to get the entire piece as a complete clean object.

If I shoot around it placed flat on each side and create two chunks in PS, I cannot get enough overlapping points to get the two chunks to merge reliably. This makes sense, as there is very little detail along the coin edges, and it's usually very uniform in appearance.

If I shoot it mounted vertically, I can usually get a decent build of the whole coin, except that I have to secure it somehow to keep it in that vertical position while I shoot it, and I would also like to see that part of the coin that is bearing the support. I have tried to shoot the coin vertically in two passes with the mounting point moved to a different location on the coin for the second pass; and I can get each chunk to build correctly on their own. But I cannot find a way to get PS to align the chunks correctly so that the second chunk with 'fill in the gap' created by the mounting point from the first chunk. Usually it still aligns the two chunks in the exact same shooting positions. I have tried masking out the mounting point in both chunks, but that doesn't seem to align at all.

I am only using the standard edition, so I do not have the option of defining correspondence points between the two chunks. But I would have thought that PS could still recognize enough overlapping information between the two chunks to figure out the alignment.

Are there any ideas out there on how to get this to work? I am stumped at this point.

Thanks! -Chad

202

General / Compact Canon CDHK RAW & Lens Distortion

« on: July 06, 2013, 08:03:44 AM »

I don't think this specific question has been answered before, apologies if it's been covered already.

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. With most cameras this is the expected behavior, aside from some cameras that bake in the distortion correction into their RAWs as well.

Will Photoscan still calibrate correctly for these DNG versions from this camera? I would assume that I would not want to apply any distortion correction in another program before sending it to Photoscan, right?

I know Photoscan should normally handle this as expected, I just wasn't sure in this case, since this camera normally can't shoot RAW.

I'm attaching jpg/dng versions at 28 and 51mm to show the difference between the two versions. Thanks for any info. I imagine it will probably be fairly obvious when I test it out anyway.

-Chad

203

General / Re: Getting Holes...Need More Photos?

« on: July 06, 2013, 03:06:17 AM »

Follow up:

I found a neat trick to get rid of the black holes in the texture via an older forum posting from Lee...export the texture and re-import it. Worked exactly as hoped.

Is this an undocumented 'feature'? ;-)

http://www.agisoft.ru/forum/index.php?topic=446.0;prev_next=next#new

ps. and cheers, Lee...very helpful tip!

pps. I've seen various forum postings about trying to add to the documentation or produce more tutorial videos, but have not seen any actual outcome...is it possible to start adding some of these tips and gotchas into the wiki pages at least? I think about half of what I've learned so far has come from this forum.

204

General / Re: Getting Holes...Need More Photos?

« on: July 05, 2013, 01:10:54 AM »

Thanks for the tips, Alexey. I am going to try to re-shoot this over the weekend and see if I can get a better result. I agree that the black holes are likely from me not capturing a direct angle into those recessed spaces.

I'll try to stabilize the camera a bit more so I can use a lower ISO as well...maybe I can sneak in a monopod. ;-)

I'll try to follow up with the improved results.

Thanks again, -Chad

205

General / Getting Holes...Need More Photos?

« on: July 03, 2013, 09:13:09 PM »

First time post...how exciting! I just want to start with a huge appreciation to all of you who answer questions so readily in this forum, it is an amazing resource for a great piece of software. So far I've made it through about half of the messages in the forum, lots of helpful info!

I've just starting getting familiar with SfM and Photoscan and have been experimenting with a variety of shooting styles and subjects, mainly with an emphasis for archeological presentation.

I photographed this sarcophagus at a local museum recently, but I am getting some holes and other artifacts in the texture (see right side in screenshot), no matter what method I use for generation (Average, Mosaic / Generic, Adaptive Orthophoto, etc). The geometry is generally coming out okay, but if I choose a higher quality mesh, I start to lose some feature detail, and I'm getting better results with low quality. I shot raw and have boosted the shadows quite a bit, so there isn't much that is dropping into darkness at this point. The photos are a bit noisy, so that could be creating some issues with the solve.

The camera alignment also seems to be okay for all of the photos, as you can see in the screenshot.

My guess is that I need take more photographs from a 3/4 angle along the main length of the sarcophagus in order to get more visual data for the 'nooks and crannies'...and probably try to work at a lower ISO to get the noise down a bit more.

Does that seem like an accurate assessment? Any other thoughts from the brain trust out there?

Cheers, -Chad