Messages

121

Feature Requests / Re: PTEX support

« on: March 22, 2013, 05:52:20 PM »

I just thought I would bump this with a gigantic +1

I'm so over faffing about with gigantic unusable UV maps. That is a general complaint not specific to PhotoScan :-)

122

Feature Requests / Re: Baking Displacement

« on: March 22, 2013, 05:48:29 PM »

I am not sure if I understand correctly what you want to achieve. Do you want to create a difference map between a high-reolution mesh and a lower-resolution mesh?

Essentially, yes. A displacement map is a common way to encode high resolution geometry on a low resolution mesh. Basically, you have a low resolution base mesh plus a texture map that is used to deform it so that it matchs the original high resolution geometry. This has various performance advantages over just working with the original high resolution geometry.

123

General / Re: Planar surfaces and sharp edges

« on: March 19, 2013, 11:11:26 PM »

Its a bit difficult to tell from your images exactly what is going on. It might be helpful to post a screenshot of your model in PhotoScan with the texture turned off so we can see what the geometry looks like. One of the original images would also be helpful to see what you are trying to capture without distortion.

I'm a bit worried that you are trying to force a fundamentally 3D object (tunnel) into a mostly 2.5D box (GIS). Trying to flatten a more or less cylindrical tunnel on to a 2D orthophoto/terrain model is going to introduce a huge amount of distortion, and is probably not the right thing to do, unless you are only looking at a small section of the wall. For this kind of fracture characterization you may want to look at a more 3D analysis using something like Split-FX.

124

General / Re: Photoscan on a laptop

« on: March 19, 2013, 07:59:02 PM »

Sager (http://www.sagernotebook.com/) makes really nice laptops. Their laptops are much more customizable than an equivalent Dell, almost as many options as when setting up a desktop. You also see rebranded versions of their systems from a lot of the boutique gaming system vendors.

125

General / Re: At what step are "ground control points" or markers taken into account?

« on: March 15, 2013, 11:29:07 PM »

I've been trying to sort this out too. Assuming I have independently measured ground control points and I want to use guided marker placement is the correct workflow:

• Align photos
• Build geometry (low-res for guided placement)
• Place markers
• Optimize camera parameters & point coordinates
• Build geometry (including depth maps for final model)

Although only the intrinsic camera parameters are listed I'm assuming the optimize step also optimizes the extrinsic parameters. Before and after inspection of the camera transform matrixes suggests this is the case and it certainly seems like the right thing to do. I'm also not clear on how the "Update" function on the Ground Control panel integrates into this?

Step 5 is necessary because all of the camera parameters have changed since the geometry was originally built in step 2.

126

Bug Reports / Re: Large coordinates truncated in PLY

« on: March 15, 2013, 08:16:15 PM »

According to this page:

http://paulbourke.net/dataformats/ply/

which I believe is the official definition of the format, data properties need to be defined as "double" not "float" if you want double precision instead of single precision floating point values.  In both of the example files the x, y, and z coordinates are defined as "float", hence the rounding errors when trying to use the binary version. The fact that the ascii version works  seems to be an accident due to PhotoScan writing out more significant digits than it declares in the header.

127

General / Re: Thermal camera

« on: March 13, 2013, 08:12:02 PM »

Here's another good video comparing rolling shutter in a Canon 5D and Sony Nex7:

http://www.mikekobal.com/blog/?p=4095

Notice how the buildings appear to tilt as the camera pans rapidly back and forth. That blog is discussing it in the context of shooting video but the same effect applies to stills.

128

General / Re: Noise (I assume) and what to do with it

« on: March 11, 2013, 04:44:32 AM »

I don't know that it's documented anywhere but from looking at the results my guess is that PhotoScan uses some sort of a Poisson Surface Reconstruction (PSR) internally when building arbitrary smooth meshes, so I'm not sure it's a case of different algorithms. I just prefer to go straight to the source (http://www.cs.jhu.edu/~misha/Code/PoissonRecon) in order to get more control over the results. The Kazhdan and Bolitho version also gets cool new features before they show up in any of the third party tools that are based on their work. For many data sets, PSR is also much better than any of the algorithms, proprietary or otherwise, that I've found in commercial laser scanning packages.

Regardless, looking at the raw point cloud should provide some insight into how severe the noise is and perhaps where it is coming from.

129

General / Re: Agisoft PhotoScan 0.9.1 pre-release

« on: March 10, 2013, 10:11:38 PM »

This means that no conversions to 8-bit per channel are performed during any processing step.

Hi Alexey,

So if photos are import as half-precision floating point .exr files will all calculations be floating point operations? What about if photos are import from 16-bit integer tifs? Are the values converted to floats so that floating point operations can be used or are calculations done as integer operations.

I'm interested in this in the context of avoiding quantization problems in a linear scene-referred pipeline, i.e. floating point operations are good integer operations, not so much.

Thanks,

130

General / Re: Noise (I assume) and what to do with it

« on: March 10, 2013, 09:55:27 PM »

Have you tried exporting a dense point cloud and inspecting it in something like CloudCompare?

For complicated objects I don't have laser scans of I've been moving towards exporting the point cloud from PhotoScan and putting it into my normal laser scanning pipeline. Edit point cloud in PolyWorks, generate mesh with PoissonRecon and PolyWorks, UV unwrap, then reimport into PhotoScan to lay down the base texture.

131

Feature Requests / Forum improvements

« on: February 18, 2013, 08:52:34 PM »

I've been trying to follow this forum using its RSS feed. Unfortunately, the feed only includes the first line or two of each post's body so I have to constantly keep coming back to this site if a post looks like it might be interesting. It kind of defeats the purpose of having an RSS feed.

132

Feature Requests / Re: ortho and DEM generate in batch

« on: February 18, 2013, 08:48:30 PM »

You should be able to write a simple Python script to automate these sorts of tasks.

133

General / Re: Sharpness and focal length

« on: February 14, 2013, 09:19:46 PM »

In general, you want to stay away from image stabilization for photogrammetric applications. If IS is turned on your camera calibration parameters will be slightly different for each image. Essentially, you're stabilizing the image by moving the principal point around.

One other note on tape, as long as you are using a good quality tape that isn't going to leave a bunch of residue behind on your lens I don't think there is much to worry about.

134

General / Re: Sharpness and focal length

« on: February 14, 2013, 06:00:54 AM »

testing with my 24-105 is difficult because it doesn't have a zoom lock and the focal length slips over time (v frustrating)

A little strip of Pro-gaff is often a pretty effective solution to this particular problem.

135

Feature Requests / Multiple 3D Models per Chunk

« on: February 05, 2013, 12:31:05 AM »

I often find myself wishing I could have more than 1 3D model associated with each chunk. At any given time I may want to have available one or more of: dense point cloud, low-poly mesh, high-poly mesh, edited and raw versions of all of the above. Constantly having to manually save and load them from disk while trying to remember which "3D Model" is currently present in the project gets a bit tedious.