Unity3d model production specification [GO]

all of the digital models mentioned in this article are all models built with 3D Max, and even for different drive engines, the requirements for the model are basically the same. When a VR model is completed, it includes the following basic content: Scene size, unit, model classification collapse, naming, node editing, texture, coordinates, texture size, texture format, material ball, etc. must be in line with the production specifications. A model file with clear collation, saving of face number and production specification is necessary for program control management.

first of all, the production process is briefly introduced: material acquisition-model making-map making-scene collapse, naming, exhibition UV coordinates-light rendering test-scene baking-scene adjustment export.

The first chapter, the model production norm

1, before the model division of labor, we must determine the model positioning criteria. Generally this standard will be a CAD basemap. The producer must determine the model location of their division of work according to the file with the CAD basemap, and shall not make any modifications to this standard file. The CAD Basemap imported into Max is preferably in the (0,0,0) position so that the production staff's initial model is near 0 o ' map.
2, in the absence of special requirements of the case, the unit is meters (Meters).

3, delete the scene of the extra face, in the model, the invisible Place without modeling, for the invisible surface can also be deleted, mainly in order to improve the utilization of the map, reduce the total number of scenes, in order to improve the running speed of the interactive scene. such as the bottom of box, the back of the wall object and so on.

4, maintain the distance between the model surface and the recommended minimum spacing is 1 per thousand of the maximum scale of the current scene. For example: in the production of indoor scene, the object of the distance between the surface and the surface should not be less than 2mm, in the production of the scene long (or wide) for the outdoor scene of 1km, the object of the distance between the face and face should not be less than 20cm. If the surface of the object is too close to the surface, there will be a flicker phenomenon alternating between the two faces. The model and the model are not allowed to have coplanar, leaky faces and tails, and the invisible faces are deleted. At the beginning of modeling must pay attention to the inspection of coplanar, leaking surface and the reverse side of the situation.

5, can copy the object as far as possible to copy. If a 1000-face object is baked and then copied out 100, then he consumes almost as much resources as an object consumes.

6, modeling is best to use editable poly patch Modeling, this modeling method in the final baking will not appear triangular surface phenomenon, if the use of editable Mesh in the final baking may appear triangular surface.

7. Collapse of the model when a building model is modeled and textured, then the model collapses, and this step is prepared for the next baking. So in the collapse of the time to pay attention to some problems:

(1) in accordance with the "one building an object" principle collapsed, the volume of special large or conjoined building can be divided into 2-3 objects, but before the export to the building collapsed into an object, urban villages in accordance with the courtyard collapsed.

(2) with box anti-collapse object, turn into poly mode, then need to check the map has no confusion;

(3) Collapse objects, according to buildings or plots to collapse, do not collapse across the region;

(4) The name of the project according to the requirements of the strict standard naming;

(5) The centroid of all objects shall be centered, and the object will be locked after checking the position of the objects;

Note: All objects are not allowed to exceed 200,003 corners, otherwise an error occurs when exporting.

8, model naming. Cannot use Chinese name, must use the English name, otherwise in the English system will have the problem.  Parcel building models do not permit duplicate names and must be named according to specifications.

9, tree planting method with a cross-tree or simple-mode tree. When planting trees, to take into account the relationship with the surrounding buildings, can not plant trees, according to the current situation to place different tree species, location, the key building plots need to plant a simple model tree, and in situ with the corresponding planting of cross-tree (replacement); When the model tree and its corresponding cross-tree are single tree, the other cross-tree can collapse together, But the number of polygons cannot exceed 10,000.

10, the level of the model is the fine degree of the model, and sometimes we are in the mold at the time according to the specific location of the building, the importance of the building to determine the degree of accuracy of the simulation model. The building can be divided into five levels. Among them, the first level is the highest level, level five is the lowest level. The number of faces of a single object is not too large, after all, to do virtual reality, rather than make a leaflet. The number of individual objects to be controlled below 8,000 faces.

11, the mirror object needs to be corrected. To create a new model with a mirrored copy, you need to add a modified editor to fix it.

First step: You need to select the mirrored object, then go to the Utilities panel, click Reset XForm, and then click Reset Selected; Step two: Go to the modfiy panel and choose the Normal command to reverse the normal.

12, the Baked object black seam solution to the method. When baking, if the picture is not large enough, it tends to produce black seams at the edges. Handling Tips:

1) If you make a bird's eye view floor contour More complex can combine floor contour into one object into multiple materials, and then complete the whole baking of floor contour, which can save a lot of resources.

2) for the construction and topography, you must check the scale of the model map material tile, for the farther surface (or grassland), you can consider a Turaipin with a real sense of the shop, the number of tiles less.    For the far end of the ground material, if the number of tiles large, the sense of reality is poor.

chapter II, Material mapping specification

1, material and map type. We are currently using Unity3d Software as a simulation development platform, the software has some special requirements for the material of the model, in the 3dsMax we use not all materials are supported by the Unity3d software, only the following materials are supported by Unity3d software. Standard (normal material) The default universal material ball. Basically all of the simulation systems currently support this material type. Multi/sub-object (multi-dimensional/Sub-object material) combines multiple materials into a single composite material, assigning different levels of selection to an object, respectively. It is important to note that in VR scene making, the sub-material in the multi/sub-object material must be standard material. Otherwise not supported by Unity3d. All objects must be collapsed together before the model can be baked, and the new object will automatically produce a new Multi/sub-object multi/Sub-object material after collapsing. Therefore, this type of material is often used in our simulation production.

2, Map channel and map type. Unity3d currently supports only bitmap map types, and all other map types are not supported. Only diffuse Color (diffuse) and self-illumination (self-illumination, which is used to export Lightmap) map channels are supported.    Self-illumination (opaque) map channel after baking the lightmap, you need to set the channel of the map to the new, baked channel, and point the resulting lightmap to self-illumination.

3, the file format and size of the map. The original map of the building is JPG with a channel of 32-bit TGA, but the maximum is more than 2048; The map file size must be 2 N-th (8, 16, 32, 64, 128, 256, 512), and the maximum map size cannot exceed (1024x1024).  The texture map is stored in TGA format while baking.

4. Mapping and material application rules

(1) Map can not be named in Chinese, can not have duplicate name;

(2) The material ball is named and the object name is identical;

(3) The name of the parent-child hierarchy of the material ball must be identical;

(4) The same texture must make a material ball;

(5) In addition to the need to use two-sided material performance, other objects can not use double-sided material;

(6) The ID number of the material ball and the ID number of the object must be the same.

(7) If baking with completemap, a shell material will be created automatically after baking, the shell material must be changed to standard material, and the channel should be consistent, otherwise the map cannot be exported correctly.

(8) A map with an alpha channel, which must be _al to differentiate when named.

5, channel texture application rules. The model needs to be processed by the channel to produce a texture with a channel. When making a channel texture for a tree, it is better to change the transparent part to the main color of the tree, so that the color of the effective edge portion is correct when rendering. Channel textures consume more resources than ordinary textures in the same size when the program renders.   The channel texture should be named with the-al end.

chapter III, model Baking and export

model Baking

1. Scene Light

(1) Rendering method: Use Max's own light tracer ray tracing to render.

(2) Lighting effect control: The project will give a fixed baking light before baking, the height of the light, the angle, the parameters are not adjustable, you can move the light group in the top view to their own chunks, you must use the light to merge the scene and bake.

2. Baking map Style There are two ways to bake a building model: one is the Lightmap baking paste, the texture that the baking map renders with only the shadow information, not the basic texture. It is used to create a model file (such as terrain) with a clearer texture, and the principle is to overlay both the basic texture map of the model and the Lightmap shadow map. The advantage is the final model texture comparison, and can use duplicate texture map, save texture resources; The baked model can export the FBX file directly without modifying the map channel. The disadvantage is that the Lightingmap map does not have highlight information, and the other is the Completemap baking style, which has the advantage that the rendered map itself has basic textures and light information, but the disadvantage is that there is no detail texture and the texture is blurred near.

3. Baking Map Settings

①completemap baking style when making completemap baking settings, the following points should be noted:

a) The map channel and object UV coordinate channel must be 1 channels;

b) The baking map file is stored in TGA format;

using an existing channel, the default is 3, the shadow participates in baking calculations to create a new baked material file format type, target map bar.

②lightingmap baking style in Lightingmap baking settings, and completemap settings are different in some places:

a) The map channel and object UV coordinate channel must be 3 channels;

b) The shadow of the light when baking is adv.raytraced shadow;

create a new baked material, turn on direct lighting shadows participate in baking calculation turn on indirect lighting target map bar file format type Use existing channel, default is 3.

c) When baking with lightingmap, the background color should be changed to white, to avoid the case of black edges, while baking with completemap, the background color should be changed to a map similar colors.

d) after baking with lightmap, you need to change the material back to standard, then copy the newly generated map to the standard self-illumination and set the correct map channel.

4, Map UV editing must be done manually UV editing. Model Export

1, will bake the material ball to the standard material ball, the channel is 1, spontaneous light;

2. Keep all object names, material ball names, and map names consistent

3, merging vertices (size to fit);

4, clear the scene, in addition to the main useful objects, delete all objects;

5, clear the material ball, delete the extra material ball (not important map to reduce);

6, as required to export FBX (check to see if you want to play a group export);

export Actions depending on the situation

The fourth chapter, Scene model acceptance model production process model acceptance process model acceptance criteria

Fifth chapter, model backup

submit a standard document

Standard backup mode:

L, UV coordinates: storage ground type and building pre-bake editing UV coordinates;

2, Export FBX: Store the final exported ground type and building FBX file;

3, Baking map: The final map of the storage type and the final baking map of the building, TGA format, at the same time there is a good map;

4, the original map: storage and building in the production process of all the stickers;

5, Max file: The original model, did not do any collapsed, have UVW map coordinates of the file. Pre-baking model, has collapsed, the show good UV, debugging good lighting to render the tested files. After baking the model, has baked the finished, did not do any processing files. Export the model, process the baked object, merge the vertices, delete all the files that do not use the object.

Sixth chapter, project naming requirements

1, building model naming: Area name _jz_ number, such as: sh01_01_jz_01, sh01_01_jz_02 ...

2, building map naming: Model name _ number, such as: sh01_01_jz_01_01 ...

3, Terrain model naming: Area name _dx_ number, such as: sh01_01_dx_01 ...

4, Terrain map naming: Model name _ number, such as: sh01_01_dx_01_01 ...

5, Skeleton Map: To add "_al" suffix

6, need to add special effects of the glass to add "_bl" suffix; (need to add special effects to a single object baking)

Seventh chapter, create each data path

1. Storage path of aerial film

2. CAD exported max file for each region

3. Photo Information

4. Public Texture Library Data

5, all the information provided by the customer

Eighth chapter, special production requirements

1, fence, fence, rain shed, carport and so on according to the actual production.

2, photos and drawings do not match, the actual photo-based.

3, the street shop as far as possible with the actual agreement.

4, estimate the size as far as possible to use the reference in the photo, such as people, cars, trees and so on.

5, in addition to the key building as far as possible to simplify the model, stickers to do fine, can be used to map the performance of the structure as far as possible with stickers.

6, the type of greening, color as far as possible to the actual agreement.

7, the structure of the top of the building and the top of the ancillary facilities as far as practicable according to the actual production.

8, the building map when the top to leave the height of the daughter wall, to avoid the window roof to the top of the building.

9, building to make entrance.

10, terrain, greening to be rich.

11, newspaper kiosks, bus stations, substation boxes, chimneys, signal towers to make simple, to enrich the scene.

12, all the map UV size to be accurate, to avoid distortion.


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Unity3d model production specification [GO]