Quality – The 3D model must have a high level of aesthetic appeal as well as workability. If the model is intended to represent a real-world object, it must accurately represent that object. Quads and triangles must be intelligently distributed for good edge flow and clean topology.
File Formats:
● No isolated vertices ● No coincident vertices ● No coincident/coplanar faces ● Face normals point outward – by outward we mean the appropriate direction for correct rendering, with no normals incorrectly flipped. ● No empty objects – All objects should have geometry or splines or be null/control helpers. No empty objects that have names but nothing else permitted. ● Geometry must not have open edges or borders that cause see-through cracks in the model when rendered. Note: Only models inspected after June 15, 2013 are guaranteed to meet this point of the specification.
● Quads and Triangles only ● Mostly quads – The model must use quads as much as possible. A range of up to 20% triangles is acceptable for most models, but you should actively endeavor to minimize their usage in your work. Models are inspected manually to ensure excessive triangles aren’t present.
● Clean edge flow – Model must have the best possible edge flow, with sufficient geometry to meet these requirements without superfluous geometry. ● Subdividable Topology – Model can be cleanly subdividable for higher detail and still retain shape of model. ● Poles with more than 5 edges on the model are highly discouraged as it can indicate sloppy topology. ● Holding/support edges or crease sets present to retain shape after subdivision Exceptions: ● Exception for very small, insignificant objects within the model/scene: Such objects do not have to meet the criteria above. Objects such as screws, bolts, rivets, wires, and other objects which are very small in comparison to the overall model size, do not have to follow the Clean Edge Flow rules. ● Exception for one-sided objects with opacity map: Objects that represent a thin real-life object as a one-sided object, where the shape of the object is depicted via an opacity map, do not have to follow the Clean Edge Flow rules. Examples of this exception are leaves, petals, decals, paper, cloth. This exception does not apply to fully three-dimensional objects such as thin boxes. ● Crease value – Value of the Crease or Open SubDiv function within your 3D application must be 0 for all edges. ● This requirement ensures that a subdividable model, when converted to other formats, will retain the same shape when subdivided. Real-World Scale: ● Real-world scale within 1-3% – Model can use any units to achieve real-world scale. If the model does not have an exact real-world counterpart (such as a human character or an unbranded car), the model must use the size/scale of comparable objects in real life. ● Exception for exceedingly large/small models – Models of objects that have a real-world scale at a microscopic or astronomical level, such as amoebas and solar systems, are excepted from having real-world scale.
● Base of the model must be positioned at the Origin (0,0,0). ● The entire model should sit on or just above the ground plane. ● The model should be oriented to the World up-axis – The obvious “up” side of the model must be pointing toward the World up axis. In other words, the model can’t be lying on its side or upside-down when the file is opened. For objects that can be oriented in multiple ways (e.g. books, pencils, etc.), the artist is free to choose the up-axis, but this must be reflected in the presentation images so a customer’s expectations are matched by what is shown. ● The native model file must be in the same position and framing as the Search image. Additional non-native file formats that are published simply need to open so the full model is visible in the viewport with no hidden parts but do not have to match pose and framing of the native file. ● Native models are exempt from meeting the same position and framing as the Search image as long as the work needed to match the imagery is trivial (minor repositioning or rotation of model). The full model will still need to be visible in the viewport with no hidden parts. Transforms: ● The position and rotation transforms must be frozen/reset. ● All objects at 100% scale at object level. Naming and Organization: ● Descriptive and unique object names – Default object names are not acceptable. They should be changed to be descriptive of the object and easy-to-understand. ● Logical naming structure. ● Model file includes only the 3D model – No extraneous helpers, shapes, splines, or other unexpected objects not specifically needed for model functionality. ● Model includes a grouping or hierarchy for moving all objects in the model together.
● At least one material must be applied to each object to represent real-world object surfaces. The user should be able to render the model upon purchase and get quality surface representation. ● Textures applied where appropriate ● Materials and Bitmap texture files named descriptively. Bitmap filenames: Image, Pic or Picture plus a number are not acceptable. Likewise, material filenames 01-Default, Blinn01, Mat are not acceptable. ● No texture paths referenced by the model. All texture paths must be stripped from the model. UVs: ● No obvious texture stretching on model. ● UV Seams are hidden in less visible areas of model. ● People and animals must have unwrapped UVs – This standard does not apply to larger scenes where the character or animal is not the focal point.
● Transforms must be frozen/reset unless model is animated. ● Hierarchy objects must be uniquely and appropriately named. ● Rig must function as expected – Rig must perform simple deformations. ● Custom rig must include instructions – A Readme, PDF document, or other documentation on how to use the rig. Animation: ● Animation must play smoothly – No obvious glitches or hitches. ● Animation designated as looping must loop smoothly. ● No spikes in your animation graph that cause a sudden and unnatural movement or rotation during playback.