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GAME ART CREATION AND REVIEWING REQUIREMENTS.

Probably there is nothing totally new in this article, though, it will be usefull for everybody to remind the main principles that one should keep in mind when working at game graphics, especially if this is graphics outsourcing or freelance. Tips below will help you avoiding typical mistakes concerned with misunderstanding of requirements, badly thought-out pipeline and other issues. You'll also find some rules of proper presentation of your work here.

GENERAL RECCOMENDATIONS ON GAME ART CREATION

  • Once you've got the specs read them attentively, think over all points, ask questions if something is not clear, because even the smallest misunderstanding may lead to bad concecvences. When working at your model check the requirements periodically not to miss some important stage or requirement. Think over the way you are going to create your asset before starting the work not to remake significant volume of work due to the wrong approach

  • If you are provided with certain pipeline of the assets creation don't ignore it, at least when working on your first models. It's possible that you'll invent a better way to get the same result later, but trying to find a better way when working at first models usually leads to significant volume of fixes and extra work.

  • When working on models and textures remember that it's hardly possible that you get your work approved from the first time. It's also likely that you or somebody else will have a need to change or fix your model or texture. What I mean is that both model and texture should be suitable for any adjustments. In terms of modeling this means proper geometry, minimal amount of uv seams (and in the least noticable places), absence of uv stretches, uniform scale of details on uvs; in textures - properly structured psd file

  • Check model twice after you are done. First of all check it for correspondence to client's technical requirements, absence of typical technical mistakes (unwelded vertices, wrong units, objects names, pivots, e.t.c.), check if the textured model looks really good. If your client provided you examples of desired quality see if your model looks the same as the example provided, because even if a very nice work doesn't fit the style it won't be approved. 

  • Learn from mistakes. Make proper conclusions from client's feedbacks and don't make the same mistakes when working on the next models.

MODELING REQUIREMENTS

  • Attention! Client doesn't always provide high quality references. To avoid your model looking poor due to the fact that you were unable to make it detailed enough because of the bad references spend some time to look for extra references. Look for more highres blueprints, more detailed images or photos, descriptions of how this object is utlized in real life. If you don't manage - ask your customer to do this.

  • Polycount and level of details: spend your polycount budget thoroughly. Allocate more polys for large details, and less polys -for small and unnoticeable. Don't model those details that can be better done with texture and normal map, such as small bolts that look angled being modelled. If you see that the provided polycount budget is so small that you don't manage to put enough polys to large details - exceed the budget, you can always optimize your model if needed. Use 5-6 sided cylinders for thin details, 8-sided for medium, more than 8 for large. If it's supposed to make LODs for the asset use multiples of 4 (8,12,16,20, etc) - this means that you can remove each 2-nd edge at least twice.
  • Smoothing: it's imperative to adjust smoothing on your models. In most cases you can use autosmooth and fix it where needed. ALWAYS!!! review your model after you use autosmooth, because you may get undesired effects in some places. Check if you don't use more smoothing groups than needed (if you can use 3 smoothing groups - don't use 5 and more)
  • File:check if you don't have any extra objects in the file
  • Units: check if units in the scene correspond to provided requirements. If you are not provided with any specific requirements on this - use meters and make assets in natural scale, i.e. human is 1.8 meters high, e.t.c.
  • Objects scale : if there is no blueprint with dimensions of the asset - use real world objects as a guide. Check if your model is proportional.
  • Proportions: when modeling and after you are done check proportions of separate parts with the references. It happens that the geometry is right, but the proportions are wrong.
  • Pivots: if there are no requirements concerning pivots - set them as shown for buildings and characters(3dMax):
  • pivots

    If your asset contains rotating parts (wheels, doors, etc) - set pivots to the centers of the rotating parts.

  • Object location : if other is not specified, the asset should be located in the center. If it is symmetrical - it should be absolutely symmetrical related to the axis of symmetry. If there are no reasons to make different mapping for symmetric parts - uvs for symmetric parts should be identical. 

  • Geometry: Check if all vertices are welded, if there are no double edges or polys

  • Naming:  objects should be named as specified in the requirements. In case if this is not specified - create convenient names and follow some logic when naming the meshes. DO NOT name your assets as "building", "house", e.t.c. as it's very easy to get duplicate names this way. You can name your assets the same as the reference provided, for instance you are going to model the King Tiger tank. In this case name the main mesh as kingtiger. Such objects as wheels and turret name as kingtiger_wheel and kingtiger_turret. To mark left and right use “_l” (left) and “_r” (right).

  • objects naming

  • Hierarchy: If nothing is specified - make hierarchy basing on the most probable supposed usage and animation of parts of your mesh. For instance, if it is told to separate the tank into mainbody, wheels, turret and gun it's obvious that wheels and turret will be parented to the mainbody, gun will be parented to the turret. If you don't know what hierarchy is - read corresponding help topics in your modeling package.

  • Topology: check if meshes with complex shape have correct topology: shape should be represented correctly, there should be no smoothing issues, concerning the characters - be attentive at joints and face.

  • File Format: Deliver your model exactly in the format that is asked in the requirements. This means that if you are asked to deliver your models in Maya7 .mb you should deliver an .mb file that can be opened in Maya7.
  • Materials (shaders) – if other is not specified,name material the same as the file, for instance, kingtiger. If you have several textures at your mesh create a multi-sub-object material, not many different standard materials. Remove extra materials that you've got after modeling, export, e.t.c.
  • When modeling the assets that are going to use normal maps take into account following things:
    1. Normal maps allow to make beveled edges, though, it's still better to make edge bevels by geometry if there is such necessity or polycount allows. Note: to avoid bugs when making edge bevels with normal map you should separate the uvs on the edge and move them to get some space between them, otherwise you'll get a very thin, but noticeable artifact on the edge. This is concerned with the fact that normal map has different colors for different polys at the same edge. Due to the mipmapping the colors blend and result in such a bug.
    2. Normal maps plus darkened texture represent concavities.
    3. Normal maps are good for small surface details
    4. Normal maps are good to represent narrow and deep seams between the details, this looks almost perfect. Though they are not as good for convex details
    5. Normal maps are bad for large prominent details. The problem is that if you make large prominent detail with normal map it will be more or less ok when viewed in front or at some angle, but will become absolutely flat when viewed from side.
    6. Normal maps are not very good to smooth the geometry.

In general this means that you should make big prominent details by mesh, check if large details are smooth enough and don't model small details or concavities.

 

UV MAPPING RECCOMENDATIONS

In some cases it's not allowed to mirror uvs, but at the moment most of game engines support correct rendering of normal maps at mirrored uvs. Here we suppose that it's allowed to mirror uvs.

When mapping the game models the most important thing is to use uv space thoroughly:

  • most of details should have the same scale. Though, you should scale up small parts that need much details on texture (for instance, small wheels on the cart), and scale down large details that are hardly visible or have smooth surface (bottom and back polys, thin wires, e.t.c.)/ It's not desirable to scale the uvs more than twice - difference in resolutions wil become too obvious. Moreover, if you can scale something more than twice this means that uvs are packed badly, there is too much free space on uvs and you should consider rearranging the uvs.

  • remember about the mipmapping - leave at least 4 pixels between your uv parts, if possible - 6-8 pixels. You can easily check the distance between your uv parts making the uv snapshot and viewing it in ACDSEE or Photoshop.

  • map parts that will have the same or similar color close to each other. The same relates to the parts of the same detail. It's very bad when the top of a small bolt, for instance, is mapped to the one corner of the UV quad and the side - to the opposite corner.

  • if alpha channel is going to be used for transparency leave at least 10 pixels around the parts that will use alpha channel to avoid issues with mipmapping

  • locate the uv seams in the least noticeable places

  • minimize stretching. Don't make any stretching where some details with regular form (bolts, for instance) or text should be present.

  • mirror the uvs only in such places where it is not going to look too obvious. Fold all cylindric and symmetric details

  • map to the same uv space those details that use the same texture and don't have nay specific details: wires, pipes, e.t.c.

  • avoid hidden "wasted space" on uvs. This appears when some detail is located on top of another one on mesh, but is mapped to separate space on uvs, see below:

wasted uv space

Note: to avoid issues with texturing it's adviced to scale down a bit the uvs for the part located on top of another one.

  • when mapping the cylindric details take into account what texture is going to be used for this part of the model. If there should be some concentric circles or some ornament or anything like this - never map it using planar mapping - in this case concentric circles will look pixelated. You can minimize this effect, but you'll be never able to remove it at all. It'll be also hard to paint the ornament or locate the small details properly. See image below for the correct option.

     

  • proper cylindrical mapping

  • don't try to fill the uv quad anyway. If optimized uvs fit the rectangle (half of uv quad) instead of the quad - that's nice too.

  • when working on uv mapping check the references periodically to see which details are going to be painted on the surface. This is needed not to map the same surfaces to differetn uv space and vice versa - not to map to the same place some parts that need unique texture.

  • tile long details, such as wires, pipes, e.t.c.

RECCOMENDATIONS ON TEXTURING

  • be attentive to the style, check if your work is looking similarly to the samples provided by client

  • check uvs before you start texturing so that you don't have to remap the model after you've completed significan volume of work on texturing. If you don't like anything about the model or uvs - inform your client or ask if you can fix this by yourselve.
  • if you consider that uvs need to be changed as if you are allowed to remap the model: in some cases this is not acceptable (for instance, you are given a model that has already got several texture sets and you are working at variations).
  • once again ! Client doesn't always provide references of quite high quality. To avoid your model looking poor due to lack of details caused by bad quality references spend some time to look for extra references or ask your client to do this if you don't manage.
  • think over the best way to texture your model: sometimes it's better to start with normal map, sometimes - with color, sometimes - with ambient occlusion.
  • structure your psd file so that anybody can easily understand it: use layer sets, clipping masks and smart objects. Name main layer so that it's clear what they contain. Use English language.
  • name textures properly. If texture name is not specified name it the same as the object. In case if you need color, normal and specular textures (and you don't have any specs) add _clr (for color), _nm (for normal map), _spec (for specular).
  • save your textures to 24 bits tga if there should be no alpha channel and to 32 bits if it is and is used.

     

  • be carefull with small parts and surface details scale. If surface texture is too big it won't look naturally. The same relates to small details, such as bolts and seams - if they are too big the object looks cartoony

  • dirty object and dirty texture is not the same. Paint dirt thoroughly. Don't think that the more dirt there is in your texture, the better it is.

  • check if your texture is neither blurry, nor too sharp

  • use good photos for your textures. I reccomend using textures from http://cgtextures.com/

  • check if you don't use compressed jpegs: in this case yoru texture will look badly whatever you do. See below how compressed jpeg looks like (look at that "quads" - good quality texture doesn't have such):

  • proper cylindrical mapping

  • if your texture should have plenty of details, but the resolution is low and it's hard for you to paint all the details try painting the more highres texture. When working at more highres texture scale it down and check if the target resolution looks well.

  • don't leave visible seams on texture, check if everything tiles properly

  • improve your skills. Study shape, light and shadow, materials and textures of the surface, color, perspective; learn traditional painting, photography, sculpture, lighting and anatomy, color theory and design. View portfolios of other artists and companies, analyze what is good and how you can get the same or better results. As the main focus of this article is what you should check, not how to make it looking good, I'd reccomend two books:

    - focal_press_3d_game_textures_photoshop.pdf – english book on texturing
    - Оуэн Демерс. - Цифровое текстурирование и живопись.pdf – russian book on texturing

    Besides of that you can find plenty of other resources, tutorials and videos on texturing over the inet.

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