The FundamentalsConfessions of a Texture Artist

Confessions of a Texture Artist

Intro

I compare texturing to cooking, for any one dish their can be many different recipes. You need to sift through those recipes to find one that works best for you. As with texturing there are many different techniques, some are useful, some less so. It only comes with practice and experience that you find the winning recipes!

Confession 1.

Reference is King!

I cannot stress this enough! When texturing, it is good practice to have your reference images always visible on your monitor while working. Being able to quickly refer back to your reference for cross checking is vital. It is also good practice to submit your work with reference attached so supervisors/directors understand your creative direction.
Make sure to stop every 15-30 minutes to study the work that you have been doing against the reference. And do not be scared to ask other people what they think; get their opinion of your work and remember not to take it personally. Having another set of eyes looking at your work can help to really dissect and pick things apart. This can help save you and production a lot of time and you end up with a much better final result.
Before I start texturing any character or asset, I make notes of all the things that make up the many layers that go into a surface. I really take the time to study the reference and break down the elements that make up the texture. For example when I have to create a skin texture I look for:

Color modulation

- write down or make a colour palette of all the different colours you see in skin; it is never just one shade of pink.

Skin pores

- observe the many sizes and shapes.

Wrinkles

- note the number of different shapes and the depth of the different wrinkles.

Veins

- veins closer to the surface are a different colour to deeper veins and arteries.

Cuts and Scars

- the older the scar the flatter it sits on the skin.
- note the difference between types of scars: burn scars have a different look to cut scars.

Dried, Smooth Skin

- skin on the heels, elbow joints and knees tend to be more dry and wrinkly than in other areas.

Sun Damage

- look out for freckles and suntan lines.

The more detail you can dissect from a given texture, the better the chance you have recreating it.

You have probably read or have been told not to get stuck on texturing details too early. And I believe that is great advice. I treat my initial texture pass like an animator would when blocking out their animation.

I focus on laying down a solid base color first; getting coverage over the complete model. I do this by setting up a series of cameras and projecting through the model.

You can afford to be rough at this stage and not worry about texture seams. This process should only take you a few hours if the cameras are set up properly. Use programs like Photoshop to warp digital images into place and then project back onto the model using a 3D paint product like Bodypaint or Mari.

Here is a link to a good tutorial on camera projection using Lightwave. It's worth watching the whole series it a very similar process that we use at work.
If you are having to texture from concept art or texturing something to make it look realistic, the first thing you need (like I mentioned earlier) is reference. See below for a list of websites I frequent to gather such reference.

Obviously the best form of reference is if you can take the photos yourself. This is not always possible because of various reasons: time restrictions, no equipment, impossible to hire out an elephant for a day just to get hi res skin textures... So the next best thing is to use photos that people have already taken. Hopefully these photos are as high resolution as possible.

The website screengrabs show above are places that I constantly use at work. If you are having to texture a range of different assets it is a good investment and can save you a lot of time. www.flickr.com - www.3d.sk - www.cgtextures.com - www.googleimages.com

More reference = More options!

Collecting reference material is not about collecting one or two images; you need to spend quality time gathering as much material as you possibly can. Start by making a library of images that you think you will need.

At this stage start thinking outside the box; it could be shapes, tonal range, contrast, fine details in a photo which could potentially contribute to your final texture. In a production environment you will be asked to produce a series of mood boards of the images that you have found and present them to a cg/vfx supervisor. This is to make sure you are heading in the right direction from the start. These images will give you your first steps to begin your texturing. If you get this stage wrong and have not collected reference that is suitable then you can find yourself in a world of pain very quickly!

If you do have your own camera, (and I strongly recommend you do get one if you are serious about becoming a texture artist) then start taking photos in the highest resolution (RAW format) possible and start creating your own texture library. Remember, it is important to start organizing your images from the start so you do not end up with gigabites of photos to navigate through!

Moodboard examples.

moodboards

Confession 2.

Giving the model the once over.

First thing I do once the model has been approved and ready to go is give the model a good check over myself. If I am not happy with the layout of the UV’s I will get the modeling guys to change it for me or I will change it myself. Remember, it is going to be you that has to deal with painting seams in awkward places if you do not get them corrected at the start.

Normally, in larger companies the modeling team will have scripts that can be run to make sure the model is "clean" before passing it on to another department. However if you do not have the luxury of getting your model checked over, here are some of the things that you should be looking out for:
Check for flipped normals; overlapping UV’s (image)**; seams in the right areas**; a full use of the UV space vertcial and symmetrical; UV’s inside the UV space; no spilt edge borders; correct resolution on all parts and no stretching**.

Overlapping UVs

Overlaping UV’s means UV’s are folded "on top" of themselves. You want to have zero overlaps by the end of the process so that you can paint your texture over the entire surface of the model. Overlaping UV’s can also cause render issues.

Stretching

Stretching happens when your map has areas that are bigger or smaller than its relative size. To avoid stretching, always work with a checker map on your model and make sure the checkers stay square.

Seams

Seams are found where you choose to "cut" your 3d model so that it can be unwrapped into 2d. You want to have as few seams as possible because it will make your life easier to texture your model!

Confession 3.

The texture checker is our best friend!

From this simple map we are able to easily identify texture stretching, resolution problems and UV issues. A quick way of checking if the resolution will hold up is by putting a texture checker on your model and roughly working out where the camera position should be. If the checker looks pixelated then you need to add more resolution by either making your texture map larger or scaling your UV’s.

Looking through the camera enables you to play with the size of a UV shell. The idea is to be able to get about a 1/3 more resolution than you need to, from the distance of the camera. Once you have set a UV shell to be the size required then you need to match that size with all the other UV’s on the model.

Remember it is always easier to scale down your texture. If your texture is low in resolution (soft) you will not gain any details by scaling up your texture map.

Confession 4.

Choosing a texture resolution: 4k, 8k, 8bit, 16 bit?

A commonly asked question from students is, “what resolution should I make my texture maps?” I get this same question from modeling artists at work and at the end of the day you as the texture artist are going to responsible for the textures "holding up". So, do your homework before making any decisions.

The homework:

There are a couple of questions you need to know before you can honestly answer the resolution question...

How close to camera does the asset get?
You can determine this by looking at the storyboards or pre-viz.
Is only a section of the asset or the whole asset going to be close to camera?
There is no point in creating really hi res textures on the feet of a character when all you see are the hands.
Is it moving across screen and how fast?
If there is a lot of motion blur then sometimes it is not necessary to add loads of detail.
What are the lighting conditions?
If your asset is going to be in a dark environment or under atmospheric conditions then there may be no need to go crazy with detailing.

Your goal should be to always work at a texture resolution that is high enough to achieve the level of detail required for the shot and proximity of the object to the camera. This may mean that an object requires a 256x256 texture, or an 8K (8192x8192) texture or even bigger! (If that is the case you should discuss this with your lead/supervisor before proceeding).

However, only work at a resolution that actually provides the extra detail. It is pointless to create a 4K texture from a 1K source image unless you have a very good way to add in the extra detail. Otherwise, the extra pixels are just interpolation and add nothing to the quality of the final texture. In fact it will just add extra render time for other TDs!

In most cases you rarely need to go above 8K, especially if you endeavour to keep everything pixel sharp. 16 bit images are used mainly for displacement maps.

Standard resolutions for your textures should be as follows:

Small: 256x256
Small: 512x512
Medium: 1024x1024 (1K)
Medium: 2048x2048 (2K)
Large: 4096x4096 (4K)
Extra Large: 8192x8192 (8K)

Note: All images are square

Confession 5.

Weathering

One of the commonly overlooked areas of texturing photo-real objects is the lack of weathering and general aging. This is one of the easiest things to add to your texture and can really help sell the realism of an object.

This can be done by adding a multiple or overlay layer on your texture in photoshop and playing with the blend modes. (image of alphas and photoshop layers) The best way to get a good effect is to go through all of Photoshop's blending modes and to see which one is working well for the photo you have picked.
Remember when adding weathering to an object, to make sure that the scale of the detail is relative to the scale of your object.

See below for some examples of types of weathering and how to achieve the look:

Rust

A rusted look can be achieved by using a photo reference overlay. You may only need to use a small sample of the texture reference. This can be controlled by using masks in photoshop. Once again, playing with the different blend modes, you can achieve your desired look. Remember that the scale of the rust should be relative to the object.

Dust and Dirt

Dust and dirt can be done very quickly with various images and using a layer mask. Add the dirt layer to the top of your Photshop layers and paint with a low opacity and flow. By changing the blending mode or adding a filter to your dirt layer this can further enhance or make more subtle the surface quality.

Confession 6.

Layering

All source textures should be saved in a Photoshop PSD format. Where possible you should endeavour to keep your files layered so things can easily be separated back out for other texture components, i.e. SPC/DSP textures and ease of editing. There is little point in painting up a lovely detailed diffuse map, and then painting all your dirt straight on top of that same layer - This makes it hard to adjust or edit when you are asked to remove some of that dirt!

Layering is all about organizing your work in order to have the greatest amount of control of all the components that make up your final texture. This is where grouping and naming in a Photoshop file is integral in keeping yourself and work colleagues organized; there will be times when other artists will need to pick up your working files.

Obviously, with some very large texture sizes and files, using too many layers can lead to a lack of memory and even cause Photoshop to crash. The rule of thumb here is to separate layers logically. For example, your final file may end up with a base layer of paintwork colour, another with painted decals, another with tiny geometric details, and another to add some dirt/dust/grubbiness. Common sense is the rule here - if you are unsure at all, consult your lead/supervisor.

Confession 7.

Highlight and shadow removal

The reasons we spend time removing highlights and shadows is to ensure that in a 3D environment, the highlights, shadowing and any lighting variation of an object/asset is controlled by the set lighting rather than baked within the texture.

Removing the specular highlights is a fairly simple process:

Create a new layer in Photoshop and set to darken.
Using the clone tool set to 50% opacity and sample all layers activated.
Select an area close to the highlight that you want to remove and clone over the top.

Generally, specular highlights are fairly bright in comparison to the rest of the skin tone so only the small spec areas should be cloned over.

Another method you can use is adding adjustment layers with masks (curves, hue, saturation levels, brightness and contrast) in Photoshop. This same method can be applied when removing shadows.

For a quick and dirty method of shadow and highlight removal, Photoshop has an adjustment highlight and shadow removal tool that can be quite useful. You will need to spend some time with the settings to get the desired effect.

highligh_removal2
Image > Adjustments < Highlights / Shadows

Confession 8.

Creating and Normalising Spec Maps

Creating a SPC (specular gain map) can be done as follows:

Desaturate the RGB map and add a levels adjustment layer in Photoshop to make the image contrasty in order to reveal the highlighted areas which will give you your specular highlights. Remember to always be thinking about the surface (matte or glossy). As a rule the more oily and reflective the skin, the tighter the highlights. The above method may not work for you all the time depending on the surface quality of your object and some painting may be required to get desired effect.

uvoutline

UV snapshot with grey outline

Normalising SPC maps

It is necessary to normalise maps for like surfaces (leather, metal, fabric, etc.) on a given object, to ensure they react the same to light. our maps do not work in this way you will have to make further changes in Photoshop using masks to isolate areas.

With Levels or Curves in Photoshop (or whatever program you're using), normalise the map so that it is generally centred around 0.5. You can do this by making a marque selection and using the filter blur average and sampling the colour to determine the mid point.

You will probably have to mask out the different areas of your map, as there will be different values in the RGB. This enables you to manipulate the selected areas separately. I have found that it is easier to normalise the areas if I have got a 50% grey outline of my UV’s overlaying my maps.

Confession 9.

Bump or Displacement?

In many cases you will want fine details on your mesh like pores and small wrinkles. These can be added into the geometry itself and ultimately the displacement map, but doing so is inefficient and usually not necessary.

Finer details can be added in a bump map and rendered over the displacement. This takes a huge load off the rendering time since you do not have to subdivide nearly as much to get finer details to appear.

When creating a bump for the fine details I take the base RGB (diffuse map), desaturate it, then run a high pass filter in Photoshop which gives a 50% grey (mid point 0.5).This map would be used for a high frequency bump map for adding in all the fine details.

Below is a great example by Andrew Silke from The Guerrilla CG Project.

A good rule of thumb is if your detail will change the silhouette of the model, displace it. If it is not visible in the profile, add it as a bump map detail instead.

Confession 10.

Background Layer Blurring

Something that is commonly overlooked which I find is important to know, is the background blurring of your texture maps. It has been common practise when creating texture maps to fill any texture area around the active UV space with mid-grey, which does result in very tidy looking texture maps. However, this also introduces a few problems:

When rendering textured objects, some render programs (renderman) will reference a mipmapped version of your texture (the same texture stored at different resolution levels contained within the one file). If the non-active UV areas are a totally different colour from the textured area border (like mid grey), this colour may "leak" through over the texture borders and onto our object, appearing as little grey/white lines in our renders.

The best working practise is to extend the edge colour out from the UV borders to the borders of the whole texture map. There is a reasonably quick method of doing this in Photoshop using a Flaming pear plugin.

Confession 11.

Naming and terms

Naming Conventions are crucial to the organization of a given asset. For example, you're starting an environment and you name a texture "sword". You then go on to create 30+ sword textures, some from different environments. How do you distinguish between these different “sword”? Add to that, other assets that have no naming distinction between the models, rigging, particles, and so on, and you end up spending more development time trying to find assets, then actually using them.

Think about using prefixes and suffixes to denote what a file is. in the case of the “sword” texture, let us add a S_ to the front so everyone knows that it is a “sword” texture. Following that, add ArmyA_, so other artists know the “sword” is from ArmySoldierA. Including a numbering scheme such as _v01 will allow you to keep track of the versions you have created. Finally, your suffix should describe the type of map you have created: _RGB.

The final result will look like this: S_ArmySoldierA_sword_v01_RGB

Make sure to stop every 15-30 minutes to study the work that you have been doing against the reference.

Conclusion

I am hoping that some of these tips I have listed above will help you get a head start when it comes to texturing your assets. Remember that although texturing is predominantly about the creative and artistic, that you should approach your tasks in an organized and pragmatic way - marrying these different skills will make you a well rounded artist.

Observing tips like I have given you is just part of what it means to be a good texture artist. Observe your surroundings as well! Next time you are out for a Friday night beverage or a Sunday stroll, have a look around you and notice: where does dirt collect on the footpath? what color is it? How does it look in the light? Is it matte or gloss? Being aware of the textures and qualities of your environment will give you better insight and perspective when approaching your tasks at work.

Texturing can be a rewarding and an extremely creative discipline. The creative process is what attracted me to texturing and keeps me motivated every day - never are two characters the same. And each character and project present a new set of challenges for you to apply your skills too.

Wishing you guys heaps of luck! And keep an eye out for more confessions of a texture artist!

About the Author

Alwyn Hunt is a Senior Texture Artist @Double Negative in London, United Kingdom. Alwyn has a background in fine arts and has been in the digital effects industry for nine years. He has worked at a number of studios including Double Negative, Animal Logic, Sony Imageworks, The Moving Picture Company and Starz Animation . His main film credits include Alice in Wonderland, Harry Potter 5 and 6, The Wolfman, The Chronicles of Narnia: Prince Caspian, Watchmen, Robin Hood.

Comments (5)

Sebbysaid:

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Thanks for the tips Alwyn! Confession 7 is my favourite and thanks for the UV texture checker too :)

January 10, 2011

feebledsaid:

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Thank you for the article Alwyn! Conessions 5,7 and 9 helped me the most and I learned a lot of neat tricks. Also, Thanks for the checker map!