EasySCAN 3D - Out of memory error and long processing times

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Peter
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Joined: Thu 09 Mar , 2006 7:46 am
Location: Brighouse, UK

EasySCAN 3D - Out of memory error and long processing times

Post by Peter » Tue 13 Apr , 2010 10:27 am

Customer writes -
once a scan was taken my PC was taking over 7 hours to produce a cutter path!
I have since upgraded the PC (new 256 MB graphics card, 4GB of 8500 pc2 RAM and a E7400 2.8GHz CPU) to well beyond your recommended system requirements and still the PC is taking over 3 hours to produce a cutter path!

I have found that to get a usable scan of an item I am having to set the degree increment to less than 0.3 but once the scan has finished and I can see that I have an acceptable scan I hit save and get an "out of memory" error. I have sprayed the item matt black but this has had no effect.

Peter
Posts: 8
Joined: Thu 09 Mar , 2006 7:46 am
Location: Brighouse, UK

Re: EasySCAN 3D - Out of memory error and long processing times

Post by Peter » Tue 13 Apr , 2010 10:30 am

I have tried scanning an object using the following values :
Length of object : 155mm
Step over (deg) : 0.25
Scan axis resolution : 0.25
Computer Spec : Intel Pentium 4 CPU 2.80Ghz, 504Mb RAM

I could save the file as an .STL without any error message resulting in a file 87Gb.

However, I was able to replicate the out of memory message if I tried to scan with an Scan axis resolution : 0.001

In my experience, I tend not to scan with a axis resolution of less than 0.2 as there does not appear to be any improvement in the quality of the surface, it only creates bigger file sizes and takes up more processing power/time. I suspect the reason for this is that there the limitation of the laser device, you can see this by looking at numbers fluctuating on the screen, even when the laser is stationary. As you can see I have far less memory than your computer, so I suspect that adding further memory won't make any difference.

Another point to note is that if you are going to machine the scanned object back out on the machine, the typical step over values when calculating the toolpaths in QuickCAM 4D are around 1.0mm. The scanned detail less than the value used here is just going to be ignored anyway.

I think the problem you are having is with the object itself and the fact that the laser beam is simply reflecting off the curved edge, basically if you look at the object and you can see highlights then the laser is going to be effected. I have found that spraying the object with grey primer makes a big difference.

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Re: EasySCAN 3D - Out of memory error and long processing times

Post by Denford Admin » Fri 16 Apr , 2010 9:58 am

After further investigation we have found:

1. The out of memory error is related to the graphics card's onboard memory. 256Mb on board such be plenty for most scan jobs.
2. Once finished scanning, save the model before clicking next. Going to the edit screen after scanning will treble the amount of system memory used as the system creates additional copies to allow you to revert back to the original scan if something goes wrong.
3. The out of memory error from the graphics card has been improved by altering VR Milling - when you pressed Next, there was a brief period where both original and editable models were being displayed at the same time (thus doubling the amount of graphics memory used). This fix will appear in v5.33 of VR Milling.
4. Sensible maximum scanning resolutions and scanning areas should be calculated to not exceed 1,000,000 (1 Million scan points) which gives an output .STL size of around 80Mb. We've found that anything bigger will make the 3D mesh unmanageable on todays systems and software (eg, PC slows down, hangs up etc...)
So, for a linear scan, calculate number of points like this:
(X scan distance DIVIDE by Scan axis resolution) MULTIPLY by (Y scan distance DIVIDE by step over)
eg: Scanning X100 Y50 area with scan resolution of 0.1 and stepover of 0.2:
(100 / 0.1) x (50 / 0.2) = 1000 x 250 = 250,000 points

For a rotary scan, calculate number of points that will be scanned:
(X scan distance DIVIDE be scan resolution) MULTIPLY by (Total angle / Angle Stepover)
eg: Scanning X120 length at 0.25 resolution for 90 degrees at a 0.2 degree stepover:
(120 / 0.25) x (90 / 0.2) = 480 x 450 = 216,000 points

You can get an idea from the above calculations, what kind of scan sizes and resolutions are usual. If you need to scan at higher resolutions, or larger areas, then you will have to do it in sections, and use some additional software to "join" the smaller scans together.

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Denford Admin
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Re: EasySCAN 3D - Out of memory error and long processing times

Post by Denford Admin » Thu 22 Apr , 2010 12:16 pm

v5.33 is now available:
viewtopic.php?f=2&t=2860

Which addresses some of the issues

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