Skip to topic
|
Skip to bottom
Jump:
Main
TWiki.org
Welcome
Register
Main Web
Main Web Home
Users
Groups
Progress
Changes
Changes detailed
Topic list
Search
TWiki Webs
BioGeometry
Main
TModeling
TWiki
Edit
Attach
Printable
Main.June_28_2008
r1.1 - 24 Jun 2008 - 02:49 - Main.guest
topic end
Start of topic |
Skip to actions
*Progress Report (6/23/08) by Shawn Brown* --- ---+ This Past Week: ---++ Wrote Initial Framework for *spfilter* tool/app * _Note:_ adapted from sp2sp * _SPfilter_ base class * uses virtual methods for standard behavior * derived classes over-ride virtual methods for filtering behavior * good idea in principle... * each filter so far has at least one or more gotcha(s) that required writing more code than desired... * rewrote original sp2sp behaviors as *not so* simple filters * Perturb Filter * Clamp Filter * Default Filter (read commands in, write commands out) * Sub-sample filter ---++ Wrote *NEW* Ottawa *Bin Count* filter _Note:_ This is a 2 pass solution ---+++ Algorithm * Initializes spwriter header from spreader's header * Creates 3D Grid from min/max bounds and cellsizes * optional, grid lines centered on specified origin point * Allocates and zeros out grid cells (counts & valid marker) * total count = W x H x L (IE 100x100x100 = 1 million cells) * Currently 8 bytes per cell, could be reduced to 4 bytes per cell * Get Bin Counts (*1st Pass* thru file) * Bin each point into correct grid cell * Increment cell count * Restart stream * _Note:_ Had to write a new restart() virtual method for spreader, spreader_spa, spreader_spb * *BUG:* counts, bounds not properly preserved by spreadopener::reopen() * IE compute_stats() followed by reopen() overwrites computed bounds with stored bounds from file. * Restart() method works as follows * validates that file is not 'stdin', can't restart that pipe. * save file handle, counts, bounds away * call spreader->close(), cleans up reader state, doesn't actually close file handle. * call seek() to reset file pos at start of file * call spreader->open() on saved file handle * restore saved counts, and bounds * Find largest z-cell in each xy column in grid * Mark that cell as valid, leave other cells invalid * Determine whether to write out each point (*2nd pass* thru file) * Bin each point into correct grid cell * if cell is marked as valid, write point out * otherwise, do nothing (IE drop point) ---+++ Misc Issues * The usual debugging / rewriting until it worked correctly * Results are good at removing a lot of the distractions * however, some building sides have aliasing problems * buildings have noticeable divots along grid cell boundaries * SMSIMP Compressed files have greatly reduced spike problems * aliasing artifacts are preserved by simplification. --- ---++ TModeling Wiki Work... _Note:_ Based on the book "Code Complete 2.0" by Steve !McConnell * Environment / Tools guide * Design goals * Layout guide * Naming conventions guide * Comments guide * Writing Self Documenting code guide * Improvements to TMV SVN guide _Note:_ As a result, I realized that I have lots of bad habits myself that need to be worked on (hungarian, ornate comments, etc.) --- ---++ Answering questions for Christian Stith * sp_viewer command line params, keyboard short cuts, GUI, menu items * sm_viewer <Ditto> * sp2sp command line params * etc. ---++ Misc * Received new books * "Curve and Surface Reconstruction" by Tamal Dey * "How to think about Algorithms" by Jeff Edmonds --- ---+ This Week: * Will check in current *spfilter* code to SVN * Will return to working on SP(+AUX) file formats * *Design Decision:* will use a byte per command instead of bit per command, will increase file size by up to 7%, but will result in greater flexibility in adding new command types and data structure objects (edges, planes, etc.) for the future. * Designing towards merged file format that allows points, vertices, triangles, planes, etc. all in one file format * Start reading my new books (see above) * Learn more about Cocones, Crust algorithm, and !DelPSC by Tamal's group. * Re-read a few papers from conference that seemed useful --- ---+ Next Week: * Probably still be working on SP(+AUX) file formats -- Main.ShawnDB - 24 Jun 2008
to top
End of topic
Skip to action links
|
Back to top
Edit
|
Attach image or document
|
Printable version
|
Raw text
|
More topic actions
Revisions: | r1.1
|
Total page history
|
Backlinks
You are here:
Main
>
June_28_2008
to top
Copyright © 1999-2024 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding TWiki?
Send feedback