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Post your Point Clouds Here!
« on: April 19, 2008, 02:39:23 AM »
Though I would start a new thread just for Clouds.

Here are a couple of some of my latest results.  Both of these scans were done with both Y & X passes.  Stitiching/striping courtesy of MachCloud!  I wish I knew more about how to mesh accurately and/or add surfaces.  I can see a lot of detail in my clouds but it would really be nice to see an accurrate fully 'surfaced' rendering.  One must crawl before they walk.

Sid
« Last Edit: April 19, 2008, 02:41:21 AM by sshneider »
Re: Post your Point Clouds Here!
« Reply #1 on: April 19, 2008, 03:17:25 AM »
Hello Sid,

> Thought I would start a new thread just for Clouds.

Great idea.

> Here are a couple of some of my latest results.  Both of these scans were done
> with both Y & X passes.  Stitiching/striping courtesy of MachCloud!

This looks like a great data set. Also appears properly proportioned. Scanned hands that have been shown in other threads have appeared to have extra long fingers.

Are the stray points from the blanket?

Can you show a photo of your camera and laser setup?

What camera and laser are you using?

What is the useful camera field of view and how far is the target from the camera and from the laser?

What is the laser diameter in the working area?

Did you take this data with the house lights on?

Try scanning a sphere and see if the cloud appears circular viewed from any direction.

Tom Hubin
thubin@earthlink.net
Re: Post your Point Clouds Here!
« Reply #2 on: April 19, 2008, 11:59:17 AM »
Hey Tom,

Getting right to the heart of the matter eh?   ;)



This looks like a great data set. Also appears properly proportioned. Scanned hands that have been shown in other threads have appeared to have extra long fingers. 

Awww Shucks but, I am but an instrument.   8)

Are the stray points from the blanket?

Yes there are.  But, I orginally was using my wood table as a background and it was worse- hence the darker blanket.  It helped reject the Zero plane points but I would like to find something better.  So far my best results have been to raise my subject about 1" above the zero plane and then set the Ignore setting to .75".  Works pretty good.  That's how the Ark was done.  The Frame was directly on the Blanket.

Can you show a photo of your camera and laser setup?

Sure, but probably not till Monday

What camera and laser are you using?
OOOOOOOOOh that's classified Area 51 security clearance stuff  ;D ... Camera = Gigaware available at a Radioshack near you- I think I paid $19.95.  It runs under the Logitect Driver so it's probably a knock-off.  $4.00 Laser came from the Ebay listing someone posted on another thread in this forum- probably made by illegal, shoe-less child labor  ::)


What is the useful camera field of view and how far is the target from the camera and from the laser?

OK, the height is easy for me to answer- around 10" (depending upon if you mean how high above the Zero Plane Vertically OR if you mean taking into account the angle of the camera and projecting a straight line from the lens to the Zero point of the laser.  10" is the diagonal dimension.  I guess this is an Isoceles triangle geometry calculation?

I'm not sure what you mean by "USEFUL" FOV?  I know what my setting is but, I don't think that's what you mean.  How do I figure this out- sorry if this is a lame question.

What is the laser diameter in the working area?

Uh, another Techie question that I'm not sure what you mean.  The laser is projecting a line on my table about 6" long.  So I guess that would be a 12" Diameter- although I'm not sure why this is important to know.

Did you take this data with the house lights on?
Unless my cat turned on the lights at my home they were off.   :D  The lights at my shop were I did the scanning were also off (sorry I just couldn't resist)  :P

Try scanning a sphere and see if the cloud appears circular viewed from any direction.

OK, I'll try it next week some time and let you know.

Regards,
Sid
Re: Post your Point Clouds Here!
« Reply #3 on: April 19, 2008, 03:10:49 PM »
Hello Sid,

> I'm not sure what you mean by "USEFUL" FOV?

The laser plane Y dimension and XZ dimension that the camera sees. You can use a ruler or graph paper in place of the laser plane and see that with the camera under normal lighting.

>> What is the laser diameter in the working area?
Quote

> Uh, another Techie question that I'm not sure what you mean.

The collimated laser is often 1mm to 2mm thick as it leaves the laser module. If there is an adjustable laser focus lens then you can adjust the laser to be skinnier at the target. A skinnier laser is more concentrated and therefore more immune to background noise (e.g. shop lights).

Is your laser collimating lens adjustable? If so, have you adjusted the lens so that the laser is skinniest near the center of the scanning range? Can you estimate the thin dimension of your laser line near the center of your target range?

> The lights at my shop where I did the scanning were off.

What happens if the shop lights are on? Can you show something scanned with shop lights off and again with shop lights on, just to see if the shop lights are problematic?

>> Try scanning a sphere and see if the cloud appears circular as viewed from any direction.

> OK, I'll try it next week some time and let you know.

A ping pong ball is spherical with a nice surface. A tennis ball or baseball would show well but these have irregularities in the surface. Still, they should appear circular from any direction.

Tom Hubin
thubin@earthlink.net.
Re: Post your Point Clouds Here!
« Reply #4 on: April 19, 2008, 04:43:48 PM »
Hey Tom,

Quote
The laser plane Y dimension and XZ dimension that the camera sees. You can use a ruler or graph paper in place of the laser plane and see that with the camera under normal lighting.

I dunno, I need to measure- I'll get back to you on this ok?

Quote
Is your laser collimating lens adjustable? If so, have you adjusted the lens so that the laser is skinniest near the center of the scanning range? Can you estimate the thin dimension of your laser line near the center of your target range?

Yes, Yes & I'd say approx 1mm.

Quote
What happens if the shop lights are on? Can you show something scanned with shop lights off and again with shop lights on, just to see if the shop lights are problematic?

OK, I will try this next week

Quote
A ping pong ball is spherical with a nice surface. A tennis ball or baseball would show well but these have irregularities in the surface. Still, they should appear circular from any direction.

Anyone know where to buy ping pong balls?  ;)

Sid

P.S.  I hope others will post some point clouds too!
Re: Post your Point Clouds Here!
« Reply #5 on: April 20, 2008, 06:03:15 AM »
Hello Sid,

> I hope others will post some point clouds too!

I wish I could. I have all the material and tool bits here now so hope to be able to build my laser triangulation gauge over the next few days. I will be attending a local amateur machinist club (http://www.cams-club.org/) meeting Thursday evening and would really like to show my laser triangulation gauge there.

After that I still have a system problem with Mach3. I have tight quarters in my apartment's small second bedroom shop. I prefer laptops to control my Sherline 5410 CNC mill and Sherline 4400 (soon to be CNC) lathe. I have been able to get Mach3 to run ok and my camera software to run ok and both to run ok simultaneously. I have also been able to get the camera to run within Mach3 for Video Window and Probing. However, Mach3 slows to a crawl, at about 1% normal speed, after either video plugin is loaded.

I have this situation on three different laptops. I may be forced to use a desktop plus keyboard plus monitor but, frankly, I have no idea where I will put all that stuff.

Tom Hubin
thubin@earthlink.net
Re: Post your Point Clouds Here!
« Reply #6 on: May 11, 2008, 06:09:55 AM »
Here is my first recognizable cloud.

It is a small key. Too small for a house key. Probably from a mailbox or large padlock.

The file was made with MachCloud. I tried both the November and December versions of MachCloud. I have had no luck yet with the meshing feature so I am just posting the cloud.

Tom Hubin
thubin@earthlink.net
Re: Post your Point Clouds Here!
« Reply #7 on: May 11, 2008, 07:13:16 AM »
Wow- I wish my first scan turned out that good!  Nice!

Looks like you need to play with the "Ignore" variable to eliminate the Zero plane (or raise the key above your table a little bit).

Also,  Meshing won't work unless the Cloud is sufficiently Decimated.  You need to Decimate a few times to reduce the point cloud density then try Meshing.

HTH,
Sid
Re: Post your Point Clouds Here!
« Reply #8 on: May 11, 2008, 04:54:18 PM »
Hello Sid,

>> Wow- I wish my first scan turned out that good!  Nice!

Well, I did qualify that by saying it was my first (recognizable) scan. 

> Looks like you need to play with the "Ignore" variable to eliminate the Zero plane
> (or raise the key above your table a little bit).

I thought I could take that out with MachCloud. I was able to set data boundaries for positive and negative X and Y and for positive Z. Attempting to set for negative Z deleted all the data before I could mark the boundary. I would prefer to leave in some table points since thickness is a necessary characteristic of a key if you want to duplicate it or catalog it.

Of course, I am just playing with a key. There is no real goal here. However, one of my customers in the mid 1980s was interested in cataloging keys to create a data base for keys used in crimes.

Tom Hubin
thubin@earthlink.net

Re: Post your Point Clouds Here!
« Reply #9 on: May 11, 2008, 05:22:56 PM »
OK, here's my theory based on playing around thus far...

I have never been able to really make the Ignore variable work correctly when the scan subject was lying directly on the table.  I DO calibrate my block to the table BUT it seems that whenever I increased the Ignor variable to a point that it would actually eliminate the zero plane, I would lose data from the subject.

This could be just my set up and the inaccuracies thereof.  My work around was to elivate the scan subject by placing a shim underneath.  Obviously the shim was smaller than the subject so it would not be scanned.

You can do some pruning in MachCloud but, it's hard to get that kind of accuracy due to the size/inability to zoom in (as of yet I hope  ;D )
I have been able to do some 'precision' pruning using Rhino but we've already been there.  Hopefully Art will be finished with LazyTurn soon and will resume work on the Video Probing package (wink wink-nod nod)  ;)

I have another idea that I want to run by you but I'm short on time right now and it should be put under a different topic- TTYL!

Sid