What is the easiest way to do shading for a vector drawing in Adobe Illustrator/Photoshop?

Question

I am doing artistic reconstructions of several animal species for a research project. I am making the drawings using vector illustration in Illustrator. I want to be able to reuse these illustrations in various contexts, and that means using vextor illustrations in which I can resize line thickness, easily edit the image, etc.

However, I also want to have shading for these images to show three-dimensionality of these animal reconstructions. For this what I have been doing is three-tone shading in Photoshop. However, if the lines are not very thin it means the shading has a halo around it when exported back to Illustrator.

My workflow is currently as follows...

1. Export vector image from Illustrator at minimal line thickness as .psd
2. Import into photoshop
3. Perform shading using layer masks for highlights and shadows, and sometimes using multiple layers of highlight and shadows when three-dimensionality is present (e.g., limbs obscuring body)
4. Save image
5. Flatten shading layers, save copy
6. Import into illustrator as layer, position as layer on top of existing image.
7. Create third group of outlines with no color, because with highlights sometimes black outlines are lightened.
8. Position new art group where needed.

A related issue is if I have to adjust the image at all, that means I have to go back and reshade the entire image again. This is something that happens a lot in my field, as images always have to be adjusted as new data becomes available or if old drawings depict the animal's anatomy wrong and have to be fixed. This isn't as dire as it always sounds, for example in some cases I can get away with just altering some parts of the image, but quite often I can't salvage large parts of the previous image.

For example, I had a picture of a marine animal where I made the body too short and had to move the fins back. This meant I had to reshade the fins from scratch because even though I had separate masking layers for the fins, they had been translated and I couldn't translate the shading where it easily looked natural. The shape of the fin and it's shading was completely unchanged, but I couldn't use the old shading because I couldn't easily match the old shading up to the new lines.

I'm wondering if I'm going about this the wrong way, and there is some more efficient way to shade vector art in Illustrator. I don't have a problem with shading in Photoshop, I am just trying to figure out if there is a way to avoid reinventing the wheel and having to reshade the same image over and over again every time if the image has to change, or if I want to have the same image at a different line thickness.

EDIT: Based on the comments of several users, here is my workflow with pictures

I start with a vector drawing in Illustrator.

Export it to Photoshop at very thin line widths. Shade it using layer masks.

Duplicate the shading layers. Flatten them.

Import the shaded file back into illustrator as objects and move the shading object back onto my drawing file.

Note I have to have two separate layers for outlines because I have to have an outlines with fill layer, then shading, then outlines without fill on top of that.

Except then it turns out that the dimensions of the fish have to be adjusted. This happens quite a bit as many of the major dimensions (length, etc.) are calculated using mathematical formulas, and other anatomical features like the shape of the jaws and head, etc., might have to be adjusted as more data comes in or if an error gets discovered (and because a lot of this is anatomical reconstruction, we don't have an actual animal we can just draw off of, we have to reconstruct things). E.g., I drew the mouth wrong on one based on bad data and had to fix it, but had no way of knowing at the time.

The issue is that most of the fish has not changed. The shape of the tail and dorsal fin has not changed, it is just the body that has stretched out. The issue I am running into is I cannot translate the shading around and reshade just the altered areas of the fish, I have to reshade the entire fish.

This can be seen here, I tried to move the dorsal fin mask and it is very crude, and I cannot move the tail fin mask at all.

Answer 1

It is a bit hard to tell, especially without seeing the final look you are achieving.

This is not an answer, but a couple of suggestions.

A. Keep the shadings editable as long as you can.

B. Use the clipping path. It is your best friend.

In all these examples I am putting the "shade" inside the object (clip-path).

I am not using Illustrator, I am using Corel Draw but the basic idea is the same in vector programs. The shading ideas I have are.

1. Import only the shading layers you created on Ps. Do not flatten it with the object. Then you can put inside the object the shading. Try different blending modes.

You have some basic editable capabilities here. Scaling, position, rotation, transparency, without the need of redoing all in Ps. You can also add texture this way.

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2. To keep the shading editable, you can mix two shapes.

3. Or try to use some built-in gradients.

4. Or explore using the Gradient mesh.

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5. You can add multiple shadings inside your object. Try different blending modes.

These examples are soo clumsy but you can fine-tune them and combine them.

Here is another example with a better gradient (technique 3). Just adding more colors to get a better shading.

And some ideas on techniques to shade objects.

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Here, I am just rotating the texture inside the sphere... circle. Yes. It is highly editable.

• Some highlights? Add one object, use "add" blending mode.

• Change the texture? Got it.

• Keep the original texture, and rotate the light source. Got it.

• Remove the texture. Got it.

And here is an example on how to use the same texture modified to accomplish different things.

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Edited after the comments

Let me show an example of gradient meshes. They are as editable as any node-based shape.

The first row shows the mesh itself and the second the result.

I am only using a very simple mesh of 3x3. If you only fill with white in the center row, you have a simple gradient.

But you need to start manipulating the nodes. In the second example, I just changed the position of one node. And in the third example, I also modified the length of the handlers. making "sharper edges"

So, start using 1. Gradient fills, 2. Clipping Masks and 3. Blending modes.

Here is an example I posted using gradient fills and clipping paths.

It is not great, but it just was an example for a question someone asked.

Epilogue: You do not need Ps at all.

Answer 2

I think much of this shading could easily be accomplished via Gradient Meshes. Note that Gradient Meshes are not the same as "gradients". They are more complex and can take more effort to understand and utilize accordingly.

All vector, all resolution independent, all editable....

Newer Illustrator releases also have Freeform Gradients (scroll down) which may be helpful.

You may be amazed at what's possible once you understand how Gradient Meshes work in Illustrator.

I'm not convinced that the use of Photoshop is even really necessary here.