Modeling creation basic workflow

Models (especially models with animation), as the most expressive and changing asset in WebAR/3D/VR scenes, have more requirements than other types of assets in terms of production specifications. In order to ensure the final rendering of the scene, this This section will elaborate on all aspects of the model specification.

Before talking about the model specification, two issues need to be clarified. The first one is: the difference between "WebAR/3D/VR model animation" and "traditional modeling as CG", see the following table:

Project	WebAR/3D/VR model	Traditional modeling used as CG
Number of faces (four sides)	<30W	Not limited in theory
Texture	Split UV	Its not mandatory
Animation	Strict standards	Ways supported by modeling software

The second question is: How to determine the script, reference image/reference video, the reference basis mainly has the following four points:

• Three-view design of the original painting;

• Three-view photos of reference objects;

• Animation reference video;

• Demand script.

After clarifying these two premises, the following will enter the specific creative workflow of model animation.

1. Software used in modeling

Common model animation software: 3ds Max, Maya, Blender, etc.;

Common carving software: ZBrush (you need to pay attention to the number of model faces after using the carving software)

Common texture processing tool: Photoshop

Common asset and texture creation tools: Substance Painter, Quixel Suite

Other professional modeling software: Use SketchUp, SolidWorks, AutoCAD, Inventor and other modeling software to export FBX, reduce the surface and check whether the model and animation are correct in common modeling software.

2. Blank Model Creation

• Use four-sided faces. Triangular faces are not recommended (especially for models with animation), and polygonal faces are not allowed; (Note: If the model does not have animation, the use of triangular faces will not have much impact; if the model has animation , If it is unavoidable to use a triangular surface, you need to pay attention to check whether the model animation will be interspersed, it is recommended to place the triangular surface in a position that is not easy to see)

• Only supports Polygon modeling (polygon modeling), not NURBS modeling (surface modeling)

• Modeling with right-handed coordinate system;

• The model making unit is unified: meter (M), the specific settings are as follows: It is recommended to make a model with a size of 10-50 units;

• The model coordinate center point belongs to the origin of the world coordinate system (the origin of the modeling software coordinate system); the model coordinate center point needs to be placed in a suitable position of the model itself, click here for the specific modification tutorial;

• The vertices of the object are in a closed state;

• Face number requirement: It is recommended that a single object model be controlled within 5W four sides, and the scene should be controlled within 30W four sides; and for scenes with animation, it is recommended to be less than 20W four sides;

• Do not allow overlapping surfaces (to solve the problem of flickering patches in the model), double vertices, etc.;

• The normal direction needs to be unified. Please be sure to pay attention to the normal direction problem; (Solve the problem of the model texture display disorder, if the model texture display error, you can try to change the normal of the wrong part)

• After the smoothing group, the model is not allowed to appear black surface, and the black surface can be avoided by adding the line card;

• Use English for the model grid name;

• Keep the distance between the model surface and the surface. The recommended minimum distance is one thousandth of the largest scale of the current scene; if the surface of the object is too close to each other, the flickering phenomenon of the two surfaces will appear alternately. Coplanarity, missing faces and negative faces are not allowed between the model and the model, and the invisible faces should be deleted. In the early stage of modeling, we must pay attention to checking the coplanar, missing and negative conditions;

• Delete the redundant faces in the scene. When building the model, the invisible parts do not need to be modeled. The invisible faces can also be deleted. The main purpose is to improve the utilization rate of textures and reduce the number of faces in the entire scene to improve the interactive scene. The operating speed.

• Try to copy objects that can be copied. If an object with 1000 faces is baked and copied out 100, then the resources consumed by it are basically the same as the resources consumed by an object;

• Carry out the collapse operation of the model. After the model is modeled and textured, then the model is collapsed. This step is also to prepare for the next step of texture production;

• For a particularly large or conjoined model, it can be divided into 2-3 objects, but before exporting, it must be collapsed into one object according to the model;

• Use Box to collapse the object and switch to Poly mode. At this time, check whether the texture is disordered;

• Mirrored objects need to be corrected: To create a new model using mirror copy method, you need to add a modification editor to correct it. You need to select the mirrored object, then enter the Utilities panel and click Reset XForm, and then click Reset Selected; enter the Modfiy panel and select the Normal command, and then you can reverse the normal;

• Avoid using unconventional systems that come with modeling software, such as curves or hair systems (Hair, Yeti, Haitrix, HairFarm, etc.) to make hair, but need to use Polygon models and textures to express;

• The model must not have holes or thorns. The part of the model structure must be displayed separately, and the structure must not be unified. The accessory model must be in the correct position with the main model and must not be interspersed randomly. The thin part of the model must not be a single piece. The display must be displayed in a complete thin model;

• After the model is completed, use the reset command (reset Xfrom) to avoid scaling and deformation, and then convert the model to Mesh or Poly mode (for models with animation, this step must be completed before animation)

• Avoid interspersing models, and delete partially overlapping or interspersed models or faces, as shown in the following figure:

Left: interspersed; middle: not interspersed; right: interspersed part shows mess;

Left: interspersed; Right: not interspersed;

3. Texture map Creation

• The platform currently supports PBR rendering. PBR rendering brings more realistic model effects and a standardized workflow for art creation. NPR rendering of cartoon materials and Unit materials that are not affected by lighting will be added later;

• When making the model, it is necessary to create a new asset and assign the relevant mesh. A single model mesh without texture and UV is not allowed;

• Ideally, please try to reduce the number of model materials, it is recommended to be less than 10;

• It is necessary to convert materials other than "Standard Standard Material" and "Standard-based Multidimensional Material" to standard materials. For example, the VARY material of 3DS MAX does not support;

• The sub-material in the Multi/Sub-Object material must be the Standard material;

• The names of assets and textures are in English and cannot have duplicate names;

• The shader naming is consistent with the object name, and the naming of the parent and child levels of the shader must be consistent;

• Shader naming: consistent with the object name, a single shader can control a single or multiple objects. For multi-dimensional sub-materials, the material ID must be set in strict accordance with the object ID number, and no repetition, confusion, skipping and empty ID numbers are allowed, as shown in the following figure:

• Texture size: no more than 2048x2048, it is recommended to use a power of 2 size for the texture;

• Texture format: without transparency channel: JPG (generally, Photoshop export quality is set to 80%); with transparency channel: PNG; (generally, ensure that the texture is less than 2M); finally, it is recommended to compress the image on the basis of ensuring the model effect Size and use other tools to compress the image quality;

• UV development: UV must be flattened, and UV split reasonably (to avoid UV breakage or UV reverse), and UV should account for more than 80% of the entire texture; generally speaking, there are two situations, for example: (a) House model Production: After making the blank model of the apartment type, assign material and texture to the mesh, then display UV and make texture; (B) Cartoon animal model making: After making the animal white model, assign material to the mesh, then display UV and hand-painted texture;

• The texture UV must not be fragmented, the separated UV map must be a block, and the texture channel and the object UV coordinate channel must be 1 channel;

• The texture map UV channel needs to be exactly the same as the object UV channel;

• Setting of texture path: support relative path and absolute path •

• Minimize the number of model textures; require a good layout when UV is displayed; for example, the UV texture of Netease Onmyoji model:

• The model map only supports diffuse map (Diffuse), transparency map (Transprent) and normal map (Normal). The settings are as follows:

• By understanding PBR rendering, we can see that the textures supported by the model include not only diffuse textures, transparency textures and normal textures. How to use multi-texture models in the platform, click here to view the tutorial; •

• Texture production: At present, the production of textures generally includes three methods, namely traditional hand-painted textures (drawing various details in the textures, such as shadows), and baked textures (arrange the lights in the modeling software in advance, and bake them with shadows) Effect map), made in the material map making software that supports PBR (please refer to the tutorial); •

• Baking texture: The solution to the black seams of baked objects: When baking, if the picture is not big enough, black seams will often appear on the edges. Handling tips: (A) If it is more complicated to make a bird's-eye view of the building, you can merge the building into one object into multiple materials, and then completely bake the building as a whole, which can save a lot of resources; (B) For buildings and terrain, check the tiling ratio of the texture material of the model. For the far surface (or grass), consider using a realistic image for tiling, and tiling less frequently; (C) For the ground material at the far end, if the number of tiling is large, the sense of reality is relatively poor. (D) If you use Complete Map to bake, a Shell material will be automatically generated after baking. The Shell material must be changed to Standard material and the channels must be consistent, otherwise the texture cannot be exported correctly; model baking and export model baking: (A) Rendering method: using Max's own Light Tracer ray tracing for rendering. (B) Lighting effect control: The project will give a fixed baking light before baking. The height, angle, and parameters of the light cannot be adjusted. You can translate the light group to its own block in the top view, and you must use the light Combine scenes and bake. (C) Baking texture method: There are two baking methods for building models: One is the Light Map baking paste method. The texture rendered by this baked texture only contains shadow information and does not contain basic textures. It is specifically applied to the production of model files with clearer texture (such as terrain). The principle is to superimpose the basic texture map of the model and the Light Map shadow map. The advantage is that the final model has a nice texture, and repeated texture maps can be used to save texture resources; the baked model can be directly exported to FBX files without modifying the texture channel. The disadvantage is that the Lighting Map texture does not contain highlight information; the other is the Complete Map baking method. The advantage of this baked texture method is that the rendered texture itself has basic texture and light and shadow information, but the disadvantage is that there is no detailed texture and it is close The texture is blurry at times.

4. Animation Creation

• Animation support: Frame animation, Bones animation, Morph animation;

• Model animation: a single vertex supports up to 4 bone weights; click here for reference for specific settings

• Animation model format: FBX;

• FBX animation zoom cannot be zero, as shown in the following error:

• Generally speaking, after exporting the FBX file, be sure to import the modeling software to check whether the model and animation are correct;

• Generally speaking, in order to avoid too large model files, the model animation frame rate is set to 30 frames;

• Generally speaking, the special animation production functions in the modeling software (such as the modifier and reformer that come with the modeling software) are not supported after exporting to FBX; • Does not support visible animation properties;

• When using skeletal animation, you need to adopt a standard skinning technique. After the skin is made, export and import to check whether the animation is correct;

• Skeleton nodes are not allowed to have the same name;

• A bone is bound to a model mesh, and a model mesh can correspond to multiple bones; a scene file does not exceed 300 bones, and a single object does not exceed 80 bones;

• Avoid two sets of duplicate bones;

• When making an animation, the child-parent relationship needs to be reasonably standardized, and the relationship level should not be too deep, and it is recommended to not exceed two levels; (If the model appears black, you can try to modify the model animation hierarchy relationship);

• Generally, after exporting FBX, we also need to pay attention to the log output by the software, and consider whether the warning in the log will also affect the correct rendering of the animation;

• In the Key frame, the visibility should be set to Visible, as shown in the figure: Visibility is set to disabled, as shown in the figure below:

• About the time of model animation (A) Animation production starts from frame zero; (B) No negative frames can appear; (C) Animation needs to be made into origin animation; •

• FBX output is not fully compatible with all methods of generating animation, generally only supports: (A) Skin controlled by simple bones; (B) Simple shape variation Generally does not support: (A) Complex bone control system; (B) Skeletal system (except Autodesk HumanIK) generated through third-party plug-ins; (C) Animation controller, or animation generated by constraints, expressions; (D) Animation generated by simulation or particle or hair or fluid dynamics related or motion graphics

• Regarding model animation, you should also pay attention when exporting FBX: (A) Bake all skeletal animations to the basic/basic skeletal system; (B) Generally, 3D animation operators are required to cooperate; (C) If there is a complex bone control system, bake it to the basic/basic bone system; (D) If there is a skeletal system generated by a third-party plug-in, the processing method is the same as (a); (E) If there are animation controllers, or animations generated by constraints, expressions, they also need to be baked into related objects; (F) All animations generated by simulation or particle or hair or fluid dynamics related or motion graphics are processed in the same way as (c); Note: Generally, it is recommended to use Autodesk FBX Review to check first, and then upload the platform after confirming that there is no problem. Click here to download Autodesk FBX Review.

5. Model Export

We recommend using modeling software or third-party software to directly export gltf or glb files. The platform has better PBR rendering support for gltf and glb. You can refer to the following documents: (1) Common modeling software exports glTF (2) glTF Tools-glTF Tools (3) glTF model format export tutorial

• Models without animation can export Obj/FBX; models with animation must export FBX;

• The ambient light and diffuse light of the model material are set to the brightest. It is recommended that the producer change the brightness of the diffuse texture to achieve the final effect;

• Model export settings with animation (A) Regardless of whether the path of the model texture is relative or absolute, it is recommended to check "embedded media"; (B) Baking animation option. It is recommended that the producer uncheck it before exporting the FBX (reduce the size of the FBX file), and then put it in the scene for testing. If the model animation is not displayed correctly, then check the export;

(C) Choose "Binary" and "FBX2014/2015" for FBX file format

• Model export settings without animation (A) Export OBJ: For all text files, the encoding should be utf-8

(B) Export FBX: Same as "Export settings for model with animation", but do not check the options of "Animation" and "Bake Animation"; Note: When selecting the material to export, you need to select the folder path where OBJ is located;

• Other checks before exporting: (A) Change other Shader (such as baking Material) to standard Material, the channel is 1; (B) Keep all object names, shader names, and texture names consistent; (C) Merging vertices; (D) Clear the scene, delete all other objects except the main useful objects; (E) Clear the shader and delete the redundant Material; (F) Export FBX as required; (G) After exporting, check the files in the folder and delete unnecessary files; FBX only keeps the used textures and model files, OBJ only keeps the used textures, model files and MTL files; (H) The compressed model folder is in Zip format, and the folder is named in English; ( I ) It is recommended to use the default Zip compression settings of WinRAR, 7Z and WinZip when compressed into zip format;