UV Painting Project


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I'm going to attempt UV unwrapping and then painting in Photoshop for the first time.

The "Samaritan" is a prop gun for the original Hellboy movie.
Adam Savage from the US TV show Mythbusters has been making one mostly from
aluminum and I was inspired enough to see if I could make the cylinder in Cheetah 3D.

The cylinder should be blackened metal with wear at the sharp edges.



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I'm still working on the models I need, so in the mean time...

I have never been the designer of a movie prop.
I have been the guy who gets the plans and has to build the props.

So for this project I will imagine I received plans for the Hellboy gun.
So here's how I would evaluate it, and possibly suggest changes.

Hellboy Gun Observations:

1. Designed for the left hand.
•Hellboy's right hand is huge and made of stone.

2. Open chamber design non realistic.
•Normal shell casing would explode.
•Unless casing is extra thick or steel?

3. Cylinder catch is in the wrong place.
•Current locations are non functional.
•Move to functional location is possible.
•Would also make it possible to make it actually function.
•Full double action mechanism possible but Hard/Long.

Catch Position.jpg

When I originally watched the movie I did not see any of those things so it all worked fine.

But when you design something that's non fantasy you kinda
have to make sure nothing sticks out like a sore thumb.
If it was a future or fantasy weapon almost anything goes.


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Here's an almost done version, no painting yet, just a tumbled metal look.

SubD modifier made editable and then Booleans added for the cylinder "fluting" and lock notch.
I just need to add the Ratchet so the Paul has something to push against to rotate the cylinder.

HB almost.jpg


Active member
Such a cool shape. I love seeing oddly shaped pieces come together to make what, at first glance, seems to be a simple device.


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It is satisfying when it comes together.

Next time I'll try to remember not to collapse the SubD Modifier until I finish building.
Working on a med to fine mesh is not fun.

Now we come to one of the questions I'm trying to answer here.
There are some areas with "hard" edges, two from the Boolean operation and one other.

The question is, can I use UV painting to highlight them to make them look very slightly
rounded or do I have to perform more surgery to add the required geometry?
It might save some time if the UV painting process is faster/easier.

HB Cylinder.jpg


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Here's a surgically altered version and a comparison between the meshes.
The altered mesh is no longer "watertight" and I did the surgery before I Booleaned the lock notch.
Now I can't easily do any more Booleans cause it needs to be "watertight". :rolleyes:

HB surg alt.jpg



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Still no painting, just using an image from a beat up metal PBR and the UV mapper set to Frontal.
I used the image from Roughness but put it in the Base Color Channel.
Then I used Mix and Background colors to tone down the effect.
It looks good but only from this angle because of the Frontal Mapping so no animation.

I like this patina, look like it was used hard and put away wet.

HB patina.jpg


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I'm having an epiphany. 🥳

By using the UV Mapper I have already "Unwrapped" and defined my UVs.

The only problem is they are all stacked up.
The solution is one of Cheetah's selection tools Group Select.

Uncheck Seams and Creases leaving UVs checked.
With this setting you just click once on a UV island and it selects the whole thing.

Great news since every time I tried Unwrapping things are always distorted.
I remember something about Pinning UVs but that's where I get lost.

HB UV islands.jpg


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Love the part where there is some discoloration of the metal due to heat? / residue from gunpowder?
Thanks, that was a happy accident due to the way the
Cylindrical Mapping applies the material to that section,
as well as that UV islands position on the image map.

As the angle of incident increases the material "smears" giving some linear streaking.
Now I still have to save as a PDF and then paint and reload, so let's see if I can remember how.

Frank B has explained this a few times but I was too thick to get it at the time. 🤯


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Not hard at all, save UV to PDF is in the UV menu and then:

Open in a graphic program.
Load my Patina image as another layer.
Use the UV lines in the PDF as a guide.
Paint, Paint, Paint.
Save as image.
Reload new image in cheetah.
Go back and forth a million times till you get it right.

This is the first pass. Just some light wear around the fluting.

HB Cylinder wear 01.jpg


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Pass two, I added a linear component and darkened
some areas that where too bright and reflective.

HB Cylinder wear 02.jpg