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Author Topic: Digitizing  (Read 77911 times)

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Offline ger21

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Re: Digitizing
« Reply #70 on: June 07, 2007, 09:08:22 AM »
Not as it's written. It's written using VBA, and I'm not to comfortable with VB.net to do it. If someone wants to do it, I can share the code I used to create the faces. You just need to read the points and write a .dxf
Gerry

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Offline GaryB

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Re: Digitizing
« Reply #71 on: June 07, 2007, 09:26:30 AM »
Thanks Gerry
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Re: Digitizing
« Reply #72 on: June 07, 2007, 11:35:10 AM »
Tetralite
Yeah, I am getting this, I got the file of the prop to imported fairly well, but it looks like that file had some problems.
Can you send me one of your files so I can play with it, the dime one would be cool.
Have you decieded on a price?

Thanks
« Last Edit: June 07, 2007, 11:50:08 AM by WYO_123 »
Re: Digitizing
« Reply #73 on: June 08, 2007, 03:58:18 AM »
I'm thinking the price will be $150. I am doing extensive testing for the past couple of days and I am still not satisfied with the assembly enough to sell it. Have to work out some details. I am attaching the point cloud file for FDR's ear on the front of the dime. That is the one that I posted an image of earlier in this thread -- there is a giant pimple on FDR's ear lobe where an error occurred (a false surface detection). The area of this scan is (if I remember right) 0.12" by 0.12" and I had to scale it all up in order to work with it. I don't know if it will work with whatever you try to do with it.
« Last Edit: June 08, 2007, 04:01:43 AM by TetraLite »
-Mark

Offline ger21

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Re: Digitizing
« Reply #74 on: June 08, 2007, 09:36:32 PM »
I am attaching the point cloud file for FDR's ear on the front of the dime. That is the one that I posted an image of earlier in this thread -- there is a giant pimple on FDR's ear lobe where an error occurred (a false surface detection). The area of this scan is (if I remember right) 0.12" by 0.12" and I had to scale it all up in order to work with it. I don't know if it will work with whatever you try to do with it.

Is this done with the digitise wizard? My AutoCAD macro doesn't like it. All the sample files I had when I wrote the macro had a line that yours doesn't, at each direction change.

Here's a few lines of your point cloud.

0.10000,0.00000,-0.01087
0.10200,0.00000,-0.01087
0.10400,0.00000,-0.01087
0.10600,0.00000,-0.01087
0.10800,0.00000,-0.01087
0.11000,0.00000,-0.01087
0.11200,0.00000,-0.01087
0.11400,0.00000,-0.01087
0.11600,0.00000,-0.01084
0.11800,0.00000,-0.01081

My macro is looking for this line
0.12000,0.00000,x.*********xx

you go to this line
0.12000,0.00200,-0.01081
0.11800,0.00200,-0.01081
0.11600,0.00200,-0.01081

It appears that you're skipping a point each time you change direction.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Digitizing
« Reply #75 on: June 08, 2007, 11:38:53 PM »
I used the digitizing wizard that is clumped in with the other wizards under the "Wizards" menu in Mach3, version R2.0.065 and not the digitizing plug-in.

Yes, I too have noticed that it skips a point on each row, but the software that I am bringing it into (Global Mapper) does not expect any particular values in any particular order, but rather just interprets the points as absolute points with their respective elevations. It doesn't matter what order they are in because a location is a location and not dependent on which location you last looked at. I can mix up the lines in the point cloud file in any way and Global Mapper will still map each point independently from the others and end up with the same grid of x,y points at their respective elevations and use it to generate the output, which is a 3D image consisting of points and their elevations and interpolated elevations between the points. Obviously, this is not quite the same as interpretting points as adjacent locations like you would want to do in order to ultimately generate efficient G-code. To get to G-code would require another step for me that would go from point to adjacent point in the output from Global Mapper with no missing points in the grid. Global Mapper fills in the missing points as well as filling in the elevations between points, so I could generate a new point cloud by exporting one from Global Mapper that would tend to have smoothed out the original input and also filled in missing points. Of course, this doesn'tg really help the problem of the wizard skipping points to begin with, which it does in my copy of the program. You can see where the points are missing in the Mach3 toolpath display on my copy. There is a diagonal line from the end of one line to the beginning of the next line, instead of a perpendicular line like you would see if it didn't skip a point. So the wizard is in error and is decrementing or incrementing the x value (depending on which direction change you are at) at the same time it increments the y value to start the next line.

This file is probably not a good one to work with because the elevations are very small. The lowest point is (-0.012") and the highest point is (-0.006"). The image I created had a vertical exaggeration added to it in order to visualize and emphasize the elevation differences, while in reality, the max difference in elevation from the lowest to highest points is only 0.006". (I may have those numbers wrong, but it was something like that.)
« Last Edit: June 09, 2007, 12:04:30 AM by TetraLite »
-Mark
Re: Digitizing
« Reply #76 on: November 06, 2007, 07:17:17 PM »
Mark,
What input format are you using for global mapper. Seems they have a lot of them.

Roger

vmax549

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Re: Digitizing
« Reply #77 on: November 06, 2007, 09:53:59 PM »
Hi Guys, you can also have mach add the axis letters to the point file. Then if you add a g1 to the top of the file you have a simple Gcode file. Then use a gcode to dxf converter to convert it to a dxf.

Or if the points were gathered in a specific order such as the wizard does then if you add the g1 and make it a gcode file then Mach will cut it exactly like you probed it. If the surface was deep you would want to multistep it down one depth at a time to prevent gouging. But with a surface as shallow as the dime it should cut ok.

But you will have to config to add the axis letters to the file.

Just a thought, (;-) TP

(;-) TP
« Last Edit: November 06, 2007, 10:04:49 PM by vmax549 »
Re: Digitizing
« Reply #78 on: November 07, 2007, 01:49:32 AM »
Mark,
What input format are you using for global mapper. Seems they have a lot of them.

Roger

Hi Roger,
Under the File menu the click on "Open Generic ASCII Text File(s)..." and it prompts you for the location and filename of your point cloud text file. When you select your file it then comes up with a window where it asks for some settings. The first setting is "Input Type" and you want to choose "Elevation Grid from 3D point data". Set "Coordinate Column Order" to the "X..." option and set "Coordinate Line Prefix" option to "None..." (I think those are the defaults). You can click on the "Select Coordinate Offset/Scale" button to scale up the image. I usually scale things up with those settings. Leave the "Coordinate Delimiter" setting on "Auto" or select "Comma" -- it works either way. Leave the slider on the "Loose" setting since you are dealing with absolute points. Or experiment. Setting it tighter takes more time.

When it asks for a projection (in the next window) select "Equirectangular" from the list. This is because the sampling points are a square grid. The other projection types take into account various distortions in the various map type projections and have no use in this type of purely regular 3D plotting where we don't have to account for things like the curvature of the Earth.

There are many ways to project and scale and alter the display of the resulting image in Global Mapper and I can't even begin to go into what I know about it here. It just takes a lot of trial and learning and exploring.
-Mark
Re: Digitizing
« Reply #79 on: August 23, 2008, 05:33:24 PM »
After a year's delay from our last discussion here, I finally decided it was time to build a touch probe.  For a long description see here: http://www.vinland.com/Touch-Probe.html
That also brings up a couple of related questions:
What is typical spring pressure and contact resistance?  Mine is 280grams and I am surprised that the the total contact resistance varies between a few ohm up to several hundred ohms.  The higher the spring pressure, the lower the resistance.  I have carefully cleaned everything.

What is the typical contact point on the balls? The further down, the higher the contact pressure but it might also make the probe sticky.  Any research papers or information on that?
TIA
Bertho