FULL SIZE car scanning

Questions, problems, comments and tips regarding the 3d scanning process.

FULL SIZE car scanning

Postby cnc Dave » Wed Mar 10, 2010 3:34 pm

Hello all!

It has taken a long time to achieve my goal with DAVID and I must thank all that have helped including all the forum regulars, Hamilton (David reseller in Ireland) for his huge help getting smooth scanning and Sven. I have finally scanned a full size car.....

Image

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It took 5 hours in the dark at 0 degrees C to get this result. I could have kept going and done the roof, but my purpose for doing this is so I can build a body styling kit for the car in a CAD program and CNC out the new parts. I scanned the areas I need.

The above scan is 130Mb and my Intel duel core, over clocked to 3.66Mhz, 4Gb of RAM and gaming graphics card, PC could only just cope with the files. Indeed merging the scans was a very slow process. This is full size car data. My CAD program, and indeed Windows XP can only utilize 3GB of RAM so I will have to break this down so I can use it, but I just had to see it all together :0)

Regards Dave
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Re: FULL SIZE car scanning

Postby Bongobat » Wed Mar 10, 2010 4:03 pm

Hi Dave,

WOW :shock: :shock: :shock:

Great work!

Could you please post lots of details of your scanning rig. It looks like you used red laser not green is this correct? What was the wattage? What camera did you use?

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Re: FULL SIZE car scanning

Postby cnc Dave » Wed Mar 10, 2010 4:53 pm

Hi Greg,

Sure it's a red 16mw focusable laser from the DAVID shop.
Camera USB CCD black and white from the DAVID shop
Gearbox... planetary 256:1 ratio
I machined the mounting parts myself.
Ardunio board and Easy Stepper board to control the 0.8 degree /step NEMA 17 stepper
Elastic band borrowed from my father to take out any backlash in the gearbox.
DAVID 2.5.3

I got the new calibration pattern printed on white Vinyl almost 1 metre square and stuck it to glass panels for my reference scan.

I aborted the sideways scanning with the 2 tripods, it was shaking in the breeze. I ended up with the more conventional one tripod set up.

My stepper control box has 2 buttons..'scan' and 'reset'. Slow scan and fast reset to original possition.

The laser is turned on with a micro switch mounted to the gearbox.

Regards Dave
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Postby hal » Wed Mar 10, 2010 10:54 pm

:shock: Wonderfull: you have done it! :shock:

My compliment, Dave. You are the first here that demostrate how David is versatile. :D
WlaterMo found the way with his outdoor scans, and you, now are the first to cross the finishing line.

Looking at your great results, I'm more inspired to scan my car (unfortunately I've so few spare time). You encourage me.

Please, if you can and want: can you post more pictures of the scans, the alignment process and of the final result (some cool renderings)?
I think that your, could be one of the best examples of David capabilities.

Compliments again and again,
Best regards,
Mattia
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Re: FULL SIZE car scanning

Postby Marko » Wed Mar 10, 2010 10:59 pm

bloody briliant work,

I was planing of doing the same with my Triumph TR7 to help out with modifications (especially suspension mounts). it would be great if the bodyshell could be on the rotisserie that way you coud scan it all way around.
that picture is just encouragement to continue with my work
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Re: FULL SIZE car scanning

Postby cnc Dave » Thu Mar 11, 2010 8:56 pm

Thanks guys,

I'm glad to have inspired you.

Scanning big objects has raised some questions though... have a look at this and it will give you some clue..

Image

This is a face we all know....


Image

This is the face next to a car scan!

My computor..

intel duel core
366Mhz
4Gb RAM
ATI 512 Mb graphics card

When picking the points for a manual merge it could take 30 seconds for DAVID to acknowledge that you had clicked on a point on the scan.

When I tried to fuse the scans, anything above 400 res and I got the error message ‘Windows has run out of memory’.
Windows XP can only use 3 GB of RAM. RhinoCAD can only use 2GB of RAM no matter how much you have got.

How much RAM can DAVID use?

How many processors can DAVID use?

The scan is not fused. It is simply saved as one .OBJ file, it was the only way to preserve detail. RhinoCAD can not open the full, raw scan… I have to reduce the mesh to 32%. To really play with huge scans you would need one seriously fast processor running 64 bit Windows 7 PRO and 8 GB of RAM…. One very expensive PC.

Many, many moons ago, I installed Photoshop, and I can’t quite remember the detail, but you had to allocate ‘virtual memory’ for the program because of the huge rendering processes and saves, so you could ‘undo’.

Is there any way of allocating memory to a program?

Mattia... I recall you saying that you would scan a car with many small, hi res scans.... I think you would get very frustrated with DAVID crashing if you did it that way. I was scanning a square metre at a time and my computer only just coped with merging...

Your the ACE at rendering Mattia, I don't have the software for it, but I'll post some pics of the newly designed Jag when it's done :D

Regards Dave
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Re: FULL SIZE car scanning

Postby Bongobat » Thu Mar 11, 2010 9:31 pm

Hi Dave,

cnc Dave wrote:Scanning big objects has raised some questions though... have a look at this and it will give you some clue


Just to clear something up. The physical size of the object does not dictate how many verticies or faces it has. For I could scan a small 1/64th scale model of that car at the same resolution and framing and come out with a similarly sized .obj file. You could also scan the car at 640 X 480 and have a smaller sized obj file of the real car than the small car scanned at 1024 x 768. Resolution is what dictates the file size . Same as any photograph which is what we are doing. If I take a picture of a salt shaker and then with the same camera take a picture of the space shuttle. I do not need a new computer to load the space shuttle picture as the file size is similar (assuming they are saved in the same format).

EDIT: You should delete the bit of ground that you scanned as this is just making the file bigger and depending on how you scanned could confuse registration.



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Re: FULL SIZE car scanning

Postby Ben4096 » Thu Mar 11, 2010 9:52 pm

I'm very impressed.
It's great and inspiring work, thank you !
About the memory limit I think you prooved it's time for 64bit David ...

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Re: FULL SIZE car scanning

Postby cnc Dave » Fri Mar 12, 2010 2:15 am

Hi Greg,

Once again I'm going to have to give this one some thought to get my head round it... it's not clear yet.

OK, you take a photo of a salt shaker and a space shuttle with the same camera. You could print out a full size picture of the saltshaker on A4, no problem. But could you print a 'full size' picture of the space shuttle ?

I want to CNC machine full sized parts to fit this car, the scan I have is... hopefully, pretty much dimentionaly correct. When I model a new bumper on the car and click 'print', I want a full sized bumper... a hi res, full size bumper (fender).

If you can scan your model car at the same res I scanned the full size car and blow your model car up to full size, yet maintain all the detail... well you could have saved me a lot of work.

So, is it that you are saying, the reason my relatively fast computor, can not cope with my scan, is because I've scanned it at too high a resolution, not because it's huge?

It's the same res as the face... it's just massive compared to it.

I need to sleep on this one. I'm a bit slow sometimes but I get there in the end :D
Regards Dave


Ps, I do know that I left the scan of the floor in, so when I design the new bumper... I know exactly how close to the ground it is.
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Re: FULL SIZE car scanning

Postby Bongobat » Fri Mar 12, 2010 3:28 am

Hi Dave,

cnc Dave wrote:OK, you take a photo of a salt shaker and a space shuttle with the same camera. You could print out a full size picture of the saltshaker on A4, no problem. But could you print a 'full size' picture of the space shuttle ?

Yes, but you would need to scale the image. But lets say you do not want to resize. You would have to take a picture of the shuttle with a very large camera that has an imaging sensor the size of the shuttle. The document printed from that wont have to be scaled but maybe the sensor has a sensor pixel that is a square meter. It is going to be a low res image still. If we wanted to get details of some other countries space program from a satellite in space we would need a lot of resolution but not a huge camera. :wink:
cnc Dave wrote:I want to CNC machine full sized parts to fit this car, the scan I have is... hopefully, pretty much dimentionaly correct. When I model a new bumper on the car and click 'print', I want a full sized bumper... a hi res, full size bumper (fender).

No problem because David sets the measurements of your model according to the scale value of the calibration printout. But David is not going to add detail it can only extract the measurements from your camera's pixels and that is dependent on what your camera's scanning resolution was.
cnc Dave wrote:If you can scan your model car at the same res I scanned the full size car and blow your model car up to full size, yet maintain all the detail... well you could have saved me a lot of work.

If the scale model of the car is made to be accurate to the real car then yes. I think Mattia was helping someone do something along those lines: viewtopic.php?f=7&t=900 I was also tasked to scan a small scale model car that was going to be printed in a larger scale: viewtopic.php?f=2&t=713
cnc Dave wrote:So, is it that you are saying, the reason my relatively fast computor, can not cope with my scan, is because I've scanned it at too high a resolution, not because it's huge?

Yes but I would not say you scanned it at too high a resolution. I was merely clearing up that physcial size does not make the file size large the amount of pixel data does. When choosing a resolution you should keep some things in mind: How much technical resolution do you need? Do you want to pick up the holes in the window washer spray heads or will picking up the general size of the lug nuts suffice, Also Your budget for a camera that can scan at the resolution you want and is your computer going to be able to handle the data when finished. Mattia's plan was to scan many close ups of a car and that would have given him many high resolution detailed images rather than aquiring an even higher resolution camera that could pick up that detail in one shot ( if one even exists).
cnc Dave wrote:It's the same res as the face... it's just massive compared to it.

If the face was scanned at the same resolution and occupies the same amount of pixels then yes.
cnc Dave wrote:I need to sleep on this one. I'm a bit slow sometimes but I get there in the end
Regards Dave

I am known to be wrong sometimes but I think what I said is true if not someone will correct me.
cnc Dave wrote:Ps, I do know that I left the scan of the floor in, so when I design the new bumper... I know exactly how close to the ground it is.

That makes sense but I would save two copies. One with the floor and one without and align and fuse with the one without and use the one with in your CAD program when needed.

Hope I made sense,
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Re: FULL SIZE car scanning

Postby cnc Dave » Fri Mar 12, 2010 3:15 pm

Hi Greg,

I believe we are barking at the same tree.

I did not photograph a salt shaker and a Space shuttle with the same frame; I walked up to the space shuttle and took 1,000 photos.

1024 x 768 = 783,360 pixels.

If I took 10 snaps of the car that’s 7,833,600 pixels. That’s hard for DAVID to handle.


If Mattia took 100 pictures , that’s 78,336,000 pixels and DAVID would crash trying to merge them. It sure couldn’t fuse them at a hi res.

To scan a model car to scale it up 10 times the size, you would need to take 10 photos of it to maintain resolution or when you scaled it up or your resolution would be low. Would it not?

So you could take a 1024 x 768 photo of a Space shuttle and blow it up to full size ...




Bongobat wrote:cnc Dave wrote:

"OK, you take a photo of a salt shaker and a space shuttle with the same camera. You could print out a full size picture of the saltshaker on A4, no problem. But could you print a 'full size' picture of the space shuttle ?"

Yes, but you would need to scale the image.


Here in England, even with vector images, we would struggle to blow it up to bill board size! Even then we'd lose resolution.

Regards Dave
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Re: FULL SIZE car scanning

Postby MagWeb » Fri Mar 12, 2010 3:57 pm

Hi,

great work!
To reduce the filesize: go to meshlab and select all the regions owning little details (You may use the brush selection tool in the paint palette). Meshlabs simplification can be set to simplyfy only selected areas. So you will keep all the details captured.
cnc Dave wrote: I do know that I left the scan of the floor in, so when I design the new bumper... I know exactly how close to the ground it is.

Simply draw a simple low res plane in any 3D application and scale it up to the size of your car. Align it to the ground manually and erase the ground which is now represented by the low poly plane >>> lots of memory will be saved.

Just a hint
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Re: FULL SIZE car scanning

Postby cnc Dave » Fri Mar 12, 2010 5:07 pm

Thanks Magweb,

I first tried Meshlabs, hoping it could convert to a NURBs file, as it can't, I binned it and dismissed it. I shall download it again, that sounds like a great function.

I've been trying in Rhino to draw lines on the mesh and create a surfce between them but it crashes at the last second... it can preview it, but not do it, which is so frustrating. I am trying to do a whole bumper at once, I'll try smaller parts and fuse them....

My new friend Eric has offered to convert the whole file to NURBs with Geomagic. There's so many scrummy programs out there I wish I could afford them all... and had the time to learn them :D

Regards Dave
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Re: FULL SIZE car scanning

Postby Bongobat » Fri Mar 12, 2010 6:10 pm

cnc Dave wrote:Here in England, even with vector images, we would struggle to blow it up to bill board size! Even then we'd lose resolution

It was just an analogy. In the shuttle sized camera I said the pixel size might be 1 square meter and it would be low resolution but on the other hand you could use a theoretical ultra high resolution camera the size of a matchbox and take the photo far away and be able to resize the image suitably. Like I said before we are able to take pictures of the earth from space with higher and higher resolutions as the technology advances and sometimes for the intent purpose of aquiring dimensional information. :wink:

3D models are basically made of vector components and do not lose resolution when scaled. I could build a 1 centimeter long completely detailed model of a car in maya right down to the exact size hole in the window washer spray nozzel. and when I scale it up to a real size car it would still be perfect and printable.

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Re: FULL SIZE car scanning

Postby leo » Fri Mar 12, 2010 8:22 pm

Hi Dave,

Impressive results!! thank for sharing.

If you use _RebuildCrvNonUniform command in rhino then you will get simpler curves and will be easier to build surface with these curves.
Have you tried to divide the mesh in meshlab ? then will be easier to work in Rhino, Also i like the Decimation in mesh lab.

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