Carving Photographs

[Michael Rabin]

I wanted to post this since I haven't found anyone else posting similar work. I am sure others are doing this but being new to CNC I couldn't find anyone who had posted it here or on other forums. First a word of my background. I am a model ship builder and I was looking for a milling machine to cut model parts when I discovered the Cut and Carve. I was fascinated by the thought of converting pictures to bas reliefs. I thought it would be easy. As I researched I decided that I wanted a real CNC and bought the smallest Shark. Initially I was excited and bought photoVcarve only to discover it was really an etching program. Etching is great but not what I wanted. I started researching it and was told by several people that what I wanted to do couldn't be done. After spending a month researching it, asking advice and generally becoming disillusioned I discovered that there was hope. I have no cam background, no photo shop background, no real artistic background. I wasn't going to sink another thousand dollars into a cam program nor was I going to spend 8-900 on photoshop. I had an epiphany when I discovered that people were using grayscaling interchangeably with heightmapping. They are the same but they are also very different. I am going to nit pick. Grayscaling is converting a photo into a black and white picture. It is useless for carving. Height mapping is creating a grayscale map in which the computer program assigns Z axis values based on the shade of gray. I also discovered GIMP, a program that is essentially a free photoshop (If you haven't already downloaded it do so now even if you aren't currently interested in doing what I am doing). When I had this epiphany I discovered the web site CNCforFree. It led me to You Tube videos by Walter Vasquez who teaches how to use GIMP with CNC in mind. I spent hours studying his lessons and then I discovered a YOu Tube video where someone converted a Homer Simpson to a heightmap. No where could I find anyone converting photographs but if line drawings could be converted then why not pictures? It took another month of trying but I discovered a technique that I now use pretty successfully. I would be happy to go into more detail but in essence what I do is I use GIMP and create layer after layer in which I paint over the photo using low opacity of black or white to bring features out of the picture. Remember black is deepest and white is shallowest. I chose the hardest picture I could find, my dog with black and white. Babies and people I have discovered are relatively easy and I would be happy to post photos of their conversions. Dogs are hard because they have so much detail and the noses are black (deep) and the muzzles need to be white so they come out of the picture. I use PhotVCarve with a tapered 1/8 ball nose with the program set to 12% lines and 0.5 inch deep cutting (0.33 may be better but more on that in a future post). I can only post three pictures but note the original with the difficult black and whites and then the converted photo with a border. The final shows the final rendering which I think is pretty good. If anyone has a better way of doing this I would be grateful to hear and learn from you. I bought this to carve bas-reliefs of my friends pets and use it for my other hobbies. (I turn pens as well and discovered I can use it pretty well for simple inlays in the pens but have a problem. I can carve the pen blank but when I invert the image and carve an inlay it is a different size. Right now I fill the prepped wood with paint mixed epoxy. It comes out pretty well.

[BillK]

That sounds like a great work around to get to your final destination. I can understand your reluctance to spend additional funds to accomplish your goal. I originally felt the same way until I finally purchased Aspire. It is the single program to own if you are going to do a lot of this.

The process you describe sounds like it might take a while to get from point A to point B. Just for example, these two took probably less than 60 seconds in Aspire, no photoshop needed.

Photo

Carving

The photo supplies the texture. Further enhancement in terms of depth adjustment to certain sections are easily accomplished.

In the end, you have to be comfortable with which ever method you choose. I recommend Aspire as it is made to do what you are looking to do. Your method definitely looks like a good work around.

[Bob]

Michael,
Nice work!
This is the type of project I've been wanting to try, but didn't get the results I wanted.
Since I don't plan on making a lot of these, it's nice to have a more cost effective method available.
I look forward to seeing more of your carvings. And how you used Gimp.
And, how you inlay pens.
And, how you use your Shark for making ships.
Bob

[jeb2cav]

Hi Michael,

I'll join in here and say I'd like to see each of the steps. I'm familiar with Gimp - and also own Aspire. But the mechanics of the layers and different shading is something you seem to have figured out. Yes, there's a 3 attachment limit - but there's no limit on the number of posts. If you find the time, I think many of us would be interested in your approach to something like this - how you created the layers, what layers you ended up using, etc.

Thanks for sharing this though - a great pointer.

[Michael Rabin]

Aspire looks good but can it convert photographs like the one of my dog? I didn't think it could that is why I went this route. I will try to describe what I do but you need to be familiar with programs like GIMP or Photoshop. I import a photo that doesn't have a lot of shading or burn out by the flash-- the better the quality and the more detail the better the end product. I then use Color tab and Hue-Saturation to change the picture to black and white. I lighten it somewhat to make it easier to change the whites and blacks. I duplicate the layer several times so I can go back. I make these extra layers invisible. I then create a new layer- all layers are transparent. I always leave the original untouched. I only use FG and BG white and black- I don't use shades of gray. If I can get rid of the excess details around the dog I use 100% opacity of the paint brush and color the picture background black, I just barely overlap the picture of the dog- the subject of my cut. When this layer is complete I create another new layer. Now I darken the fur of the dog esp around the edges and under the chin. I use about 20% opacity (Need to play and see what works). In a new layer I recolor the snout using white, again between 15 and 30% opacity. I leave the nose and eyes alone. In a new layer I alter the eyes by eliminating any glare by first darkening the yes and then in a new layer I add spots of white (The brush needs to be small- I like the brush that has a soft edge to it so it will feather). In another new layer I work the nose, small brush again and 30% opacity to bring the tip of the nose very white and less white around it. It helps to keep or add a little darkness to the edges otherwise it looks like a piggy nose. Now I really look it over carefully thinking about the white-grey scaling. I check that all the objects I want out of the picture are white shades and the deep darker. I export the image and test it in PhotoVcarve. I critically rotate it and usually have to go back and make adjustments-- this is why I use so many layers. Sometimes the eyes just aren't right or the nose is bad so I throw the layer out and start that layer over without having to start the whole project over. It usually takes four or five exports to photoVcarve before it is right and then I have my wife look-- and invariably I am sent back to fix something she doesn't like. When the photo is right I go back to GIMP and save the file in GIMPs .xcf format. Now I do in image- merge visible layers. I then go to filters- blur- Gaussian I use a 5-15 blur on the picture to make it smoother- it needs to be slightly blurry to get rid of sharp edges in the cut. I then return to image-canvas size and increase the canvas to 110%. I center the image and click resize. I then open a white layer and place it below the picture. I now have a frame that when carved will be the highest point of the picture (It makes cutting the picture from the board easier and straighter for me, plus it creates a nice frame for the wall) I then save the .xcf file as a new file so my original work is preserved and I export it as a jpeg. In photoVcarve I import it and set the size, use 12% (It seems 500-700 lines are a good number), use a tapered 1/8 inch ballnose from Precise bits (They have been very helpful giving me advice even when they talk over my head). I set the code and check the time- I don't like cuts more then three hours- This dog of mine took about 2 hours cutting a piece 6.5" by about 7.4 inches. A note on wood. To do these you cant have a wood with a lot of grain or it detracts from the picture. It also needs to be a very hard wood- I tried Poplar, redwood, oak, Aspen, Maple and Hickory. I like Hickory because it holds a good edge and the boards generally don't have a lot of grain. They are readily available at Menards for $14 a board- 3/4" by 4' by 7 1/4". I get 4-5 cuts out of a board. (I also love maple but it is expensive and I read it tends to burn). I hope this helps and can certainly go into more detail if anyone wants it.

I would like to thank Bob Hartig for his patience and encouragement when I had questions about CNC and at times thought of seriously giving up this project. He has been great always answering my frantic emails promptly. I also owe a debt to Walter Vasquez whose You Tube videos taught me a ton about GIMP relevant to CNC.

Remember this technique creates a grayscale heightmap but you are painting over the picture the less opacity of the paint the better because it will obscure detail. Rarely I will use a very thin brush to add detail, or use clone tool to transfer detail. I don't like doing this since then I am in essence am drawing the picture.

[tonydude]

Michael,

You need a smaller stepover on your tool. Use 10% on stepover in your tool data base for ball nose bits and you will eliminate the lines I see in your stuff. I do a lot of lithophanes and always have my ball nose bits at 8-10% stepover. Check out some of my stuff on here or go to my Facebook page.

Tony

[Michael Rabin]

By stepover do you mean the line spacing or the rapid clearance gap? What is the step over?

[BillK]

Thanks for the detail.

You can download a free demo copy of Aspire from Vectric.com. It does everything the real program does except generate tool paths. I actually tried your dog photo in it earlier today and it came out well fir a first pass. I'll try it again tomorrow and post it here for you to see.

Tony is correct about 10% stepover for a 1/8" ball end mill. It gives a good finish and speed combination. I made a chart which is here on the forum which will give you stepovers for other common sizes. I'll post a link here when I track it down.

[tonydude]

Here is the tool data base stepover for ball nose bits.

Tony

[BillK]

Here's the ball nose end mill post for helping selecting stepover percentage.

http://www.cncsharktalk.com/viewtopic.php?f=4&t=1672