View Full Version : 3D Modeling with Bitmaps

Joe Crumley
04-02-2007, 07:39 AM
Could some one please explain why bitmap modeling isn't used more for 3D carving. I'm aware of only acouple of instances where bitmaps are used for carving. The now famious whiz kid "Carvewright" works totaly from bmp's.

Also there is Artcam and Enroute that uses bmp for background textures. Another program is "Photo V Carve" supported by Vetric. It seems to be limited to shallow rendering. In this process the darker parts of the images are deepest areas carved. So my question is, what are the drawbacks.

It seems much easier to scan and cut rather than building a mesh model.

04-02-2007, 07:59 AM
The drawback is that it's usually not as simple as scan and cut. Extensive editing of the bitmap may be necessary to get the results you're looking for. And this is beyond the abilities of most people. The colors or levels of greyscale of an image don't necessarily translate into the correct height or depth of the cuts needed to make. The reason that Photo Vcarve is limited to shallow cutting, is that it's designed for a specific application, cutting photos.

Also, ArtCAM's strength is using vectors, not bitmaps. And it's $7000+ :)

There's plenty of software available to cut bitmaps, if your so inclined. Mach3 will even do it.

If you want to try a package that makes extensive use of greyscale bitmaps, check out Bryce. And a series of books called "Real world Bryce" that will give you techniques for bitmap modelling that you'd never imagine.

Joe Crumley
04-02-2007, 07:16 PM

Thank you very much for the reply. I'm very encouraged. I'm also very appreciative of your technical expertise and your excellent writing ability. I know when you post, the information will be good workable and reasonable hints.

I'm now running a Ez CNC which is powered by Mach 3. Perhaps I should give Mach a look see how the bmp generator works.

I full well understand the potential difficulty of converting colors to gray scale and maintaining the proper depth. There is a demo in Photo V Carve which points out this problem. And that program does an excellent job of correcting it.

Since I'm fairly adept at gray scale manupilation in PhotoShop, it seems reasonable for me to proceed with that. Although I would like to save the 7K it cost for ArtCam, it's not the money alone. I've tried the Artcam demo on creating 3D files. It was difficult for me. This isn't a program to be used every once in a while, if time is important.

Thanks again for your assistance. I will do the investigation you suggest and keep you up to date.


04-02-2007, 08:21 PM

You might find something here...

+rhino and rhinoArt will do...

Gerry don't you use rhino?

Joe Crumley
04-02-2007, 10:02 PM
Thanks for posting.

I believe the Rhino as many of the 3D mesh programs applications are vector generated. While it's a great technical program it falls short in freehand applications.

If I may speak for Gerry, yes he is more than acquainted with Rhino. It's one of the old standard.


04-02-2007, 10:08 PM
I know my way around Rhino a bit, but don't use it. I've played with it occasionally since the very first betas of Rhino 1. The main programs I use are AutoCAD and Lightwave, but I can find my way around most CAD programs and modellers. :)

04-03-2007, 06:17 AM
Yea they are all close...

04-03-2007, 07:12 AM
If you're just doing simple 2.5d stuff, any drawing program should do shouldn't it? Or have I missed something here? We're talking about taking images and creating 2.5d 'reliefs' of them in wood/plastic ?

I did a quick play with convering an image of a rose to grayscale in the gimp, then used a quick'n'dirty home brew script to convert to Gcode, the result didn't really look like a rose, but it proved the idea could work. I just needed a better sorce image, or a better way of manipulating it I suppose.

I imagine one of the edge-finding type filters in would give you somethign workable...

I'll find the big of plastic I 'rosed' and take a pic...

Cheers, Me.

Joe Crumley
04-03-2007, 07:31 AM

What I'm looking to do is full 3D images from bitmaps.

I've been directed, by one of our group, to Mach 3.

There are aparently other software programs which also come into play. It's a search to find the best one. I'm looking for advice from those who have experience.

04-03-2007, 07:59 AM
Hi Joe,

Take a look at MeshCam, there are a few versions now including an art version, but I remember that the very first version can use bitmaps to generate a height field. It generates the gcode as output.

04-03-2007, 08:33 AM

What I'm looking to do is full 3D images from bitmaps.

? I'm confused, a bitmap is a 2.5d format effectively.. You have X and Y, and a Z 'value' which is the colour/shade.

How then are you going to create a full 3d model from a bitmap?

04-03-2007, 08:50 AM
It is not 3d but it will be more than just lines.

The colors would be the depths or heights..
I'll get an example from my other comp...

Joe Crumley
04-03-2007, 09:03 AM

I understand your confusion. The process isn't very popular at this time. Here's how it works:
The darkest area's are carved deepest. The bit moves verticaly as the image becomes lighter. The little CarveWright machine only works from bitmaps.

Thanks to David for the link to Meshcam. I'll have to give them a try. They are interesting since they offer solid works and bitmap editing. I was impressed with their description for the use of a less complex process to generate a carving code. Also it's compatiable with other programs such as ArtCam. Thanks Again.

So far I've found four programs. I may have only touched the hem of the 3D garment.

04-03-2007, 09:18 AM
The globe would be a 3d part, it was a pic on the windows os, I was just playing one day... I hope this works, it's taking a while for the upload... I have a gcode for another one it's a car.. I could not ge it to uplaod.. I think my connection is kind of bad? It's a 34' ford with all the background stuff included.. I will try it later...

04-03-2007, 09:34 AM
Got it now. :-).

That's what I thought you were talking about...

Here's a pic of my 'rose' experiment.

I started with the rose picture, increased contrast a bit, and ran it through a script I wrote in php to produce the gcode. (I use linux, so I can write command-prompt scripts in php, quick'n'dirty for trying out ideas).

The part was cut from plastic cutting board, 5mm max depth, just under 50x50mm total size, 1mm stepover with a 3mm ball-ended upcut end mill in a single pass.

It's HDPE and I climb cut it, so there was lots of 'whiskering' of the plastic surface, makes it look a bit messy, this is after picking at it with my fingernail for about 10 minutes...

I intend to go back and write a better program in C to do a two stage cut, a rough cut at 5 or ten pixel stepover, and then go down to a 'per pixel' stepover 1 or 2mm deeper for the finish cut. This is a case of too many projects, not enough time. Might get to it later in the year!

Has lots of potential, but as I said earlier, I need to look into how to modify the image to get better effect... (And get a smaller end-mill, or cut larger pieces!)

Just noticed, the part is upside down compared to the image, can't be bothered re-taking the pic, so you'll have to use your imagination! :)

Cheers, Me.

04-03-2007, 10:31 AM
Are you working from a single bitmap or do you have several photo's. There is a program called photomodeler. I haven't used it myself, but their hype sounds impressive. You take several photos from different angles, make a reference spot on each and then photomodeler builds a 3D model from combining the photos.

As mentioned before RhinoArt and MasterCAM Art work about the same and do pretty much the same things. Their not perfect, but they are a good place to start.

You may also want to look at Rhinos Form vs. Shape tutorials. Unfortunately these are not free, but the web site gives you an idea of the detail they go into. There is also Secrets of Rhinoceros (Free!). This one as at a price that can't be beat. Here they do some modeling from a single bitmap on at least one project. see http://www2.rhino3d.com/resources/

I would think the techniques in these tutorials are adaptable to a wide range of modeling environments.

04-03-2007, 10:42 AM
I tryred it... I did not like it.. It really does more than bitmaps.. It allows you to use 3 or more pics to make a 3D replica.. Ok if you can deal with 4 or more axis, or make parts and assemble.

I just didn't like it....+ I bought a laser, and do not have time for it? Go figure. I use rhino4,art,cam, and can model as fast as I can set up the laser and do all the work that goes with it... Photomodeler is a lot of work too, and you got to take good pics...

Check out this http://forums.cgsociety.org/forumdisplay.php?f=149 Really cool 3d software...(nuts)

Tony Mac
04-03-2007, 11:53 AM
Something to think about is that although the pixel colour to height conversion is very straightforward - typically black is low and white is high. The real challenge to is do the 3D Cutter Geometry Compensation over the 3D height map ensuring that the cutter does not gouge / remove portions of the shape.

Simply calculating an XY coordinate + the pixel height does not work!

Imagine placing the tip of a 1/8" Ball Nose cutter on a dark pixel that sits next to a lighter and higher set of pixels. The cutter will delete remove the surrounding material, deleting / gouging the detail.

It's gets a little harder because you can't simply look at the pixel heights in the direction the cutter is moving, you also have to check all the pixels in the region around the cutter shape, to ensure detail is not inadvertanly removed.

The Rose image kind of works (see image below) because the view is looking directly down on top of the piece with good, even lighting. Most pictures include all kinds of shadows and highlights not to mention people smiling with white teeth that instantly jump out of the picture when machined using this technique. It is possible to use the tools in PhotoShop to improve the way an image works when converted to 3D, but it's not an easy process and requires considerable skill.

We developed the PhotoVCarve Groove machining (http://www.vectric.com/WebSite/Vectric/pvc/pvc_index.htm)technique to address the issues associated with the height map not working for many pictures. PhotoVCarve does the maths for the cutter compensation to ensure the cutter doesn't remove required details. Remember yo ucan always run your images through the Free Trial version of PhotoVCarve to see what they will look like when machined.

I hope this kind of makes sense.

Tony Mac

04-03-2007, 12:05 PM
This may be just what he is looking for? the $845 pkg looks pretty good, esply if you are going to do this only...

But no way would it for bobcad/cam v21w/bobart or rhino w/art/cam...


04-03-2007, 03:09 PM
Simply calculating an XY coordinate + the pixel height does not work!

You're right there, and the result you've got would look better cut...

I don't have enough interest in doing this type of work to invest in a package, although from what I've seen of vcarve on the web and this site it is the tool for the job if I got into doing commercial sign or 'carving' work...

My interest is more of the 'can I do this myself' nature. Being a geek at heart. Like many of these things, getting a simple result is exacltly that, and creating a good result is far more complex than you first think...

I did start coding a 'version 2' of my bitmap-gocde conversion that stuck the image into a huge array, and then lofted tool shapes into another array based on the image, but I quickly found that anything over a 100x100px image ran cgi mode php out of resource, and that's as far as I got! :)

If I get keen I might have another look at it,

04-03-2007, 03:28 PM
Hey, Tony Mac..

Just watched the flash video demo for photovcarve. That is a great looking user interface for the process. If I had a newer windows machine at home than my old clunker laptop I'd be downloading the demo now...

Do you know if it runs under wine?

04-03-2007, 04:53 PM
I also ran the Rose in PhotoVCarve, and looks pretty good.

04-03-2007, 05:56 PM

What size/type of tool and dimensions did you use for the simluation?

And Joe, do you mean photovcarve, or is there another product?

Curiosity is getting the better of me, might have to download the demo onto a PC at work. ;).

04-03-2007, 07:10 PM

What size/type of tool and dimensions did you use for the simluation?

And Joe, do you mean photovcarve, or is there another product?

Curiosity is getting the better of me, might have to download the demo onto a PC at work. ;).

Yes sorry i did mean PhotoVCarve. (I corrected it above)

I used a 1/8" round nose at 15% stepover