We process large point sets and meshes with StreamingModules. The documentation there has lots of example scripts for demos.

This page will include some of the best examples and pictures of step-by-step.

-- JackSnoeyink - 01 Jun 2008

Processing Data

A simplified view of the point stream of the 5x5 tile "square":

Noise Reduction

If we convert the file to a mesh right now:

spdelaunay2d -i original_file.spb -osmb | sm_viewer -ismb

the file that comes out is still a little noisy, as you can see below:

So instead we start out by filtering the points, which will reduce a lot of unnecessary noise.

spfilter -i original_file.spb -o filtered_file.spb -ottawa -cellsize 1.0 1.0 1.0 -orig 0.0 0.0 0.0

Running this program will unfinalize the data, so it is necessary to run spfinalize to refinalize the file.

spfinalize -i filtered_file.spb -o finalized_file.spb

The data is now refinalized. Next we run spdelaunay2d to create a delaunay triangulation mesh of the filtered and finalized data points.

spdelaunay2d -i finalized_file.spb -o triangulated_file.smb

A view of the filtered mesh we have right now:

To make it even cleaner, we can simplify it using smsimp. We will use 1% (0.01) of the original data, which we enact with the -t parameter:

smsimp -t 0.01 -m 16 -n 10000000 -i triangulated_file.smb -osmb -o simplified_file.smc (This should take a relatively long time, depending on your computer and the file used)

Now we can view the simplified, filtered mesh:

Shortest Paths

Note: Shortest paths modules are currently not fully functional when working with actual Ottawa data. They will run fine on the mesh file in the ShortestPathsDemo.

To calculate shortest paths, we first need to convert the file back into a usable format:

sm2sm -i compressed_file.smc -o shortpathfile.sma

Now we can calculate the shortest paths, starting by rearranging all the points:

order.exe -i shortpathfile.sma -o reordered_file.sma -s 0 0 0

Next we'll run the file through fm , which will compute the shortest path gradient for each individual triangle in the mesh:

fm -i reordered_file.sma -o gradient_file.sma -s 0 0 0

As the final step, we run the file through reverse_reader, which will compute the shortest path, and output the path into a file as a string of points. Use the -s flag to select your destination point (x y z).

reverse_reader -i gradient_file.sma -o shortest_path.txt -n 200 -s 100 100 100

For more information, visit ShortestPathsDemo.

CPU Usages

* approximate values

Time is coming soon. I can't use the computer clock and I don't have a watch, so I'll have to get this tomorrow.

Computer Specifications: 32-bit, 2.66 GHz processor, 2 GB of RAM

Original File Specifications: 869.98 MB, "square.spb"

*****************************************************notes******************************************************

And now I have run out of information. Other ideas - have a section that has the whole paragraph combined into just a few command lines, like this:

spfilter -i original_file.spb -o filtered_file.spb -ottawa -cellsize 1.0 1.0 1.0 -orig 0.0 0.0 0.0 | spfinalize -i filtered_file.spb -ospb | spdelaunay2d -ispb -osmb | smsimp -t 0.01 -m 16 -n 10000000 -ismb -osmb | sm2sm -ismb -o finalfile.sma

which gets you all the way to shortest paths. (For some reason that line isn't working... do you see something wrong with it? shortest paths line would be:

order -i finalfile.sma -osma -s 0 0 0 | fm -isma -osma -s 0 0 0 | reverse_reader -isma -o shortest_path.txt -n 200 -s 100 100 100

And compress the file for ease of use:

sm2sm -i simplified_file.smb -o compressed_file.smc

Program	Peak Memory Usage	I/O Read	I/O Write
sm_viewer (unsimplified data)	35.2 MB	1.64 GB	116 bytes
smsimp (0.01)*	671 MB	683 MB	1.64 GB
spdelaunay2d	2.97 MB	44.6 MB	111.1 MB
spfilter	259 MB	1.7 GB	573 MB
spfinalize	20 MB	1.13 GB	573 MB