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Modeling breakdown

This write-up is a summary of the different modeling processes and the reasons they were used to create specific parts of the models. The amount of planning and research required varies based on the complexity of the project. Creating a rough outline of the intended workflow can help evaluate how technical constraints may affect the individual processes. Thinking about how the asset will be used in-game, along with the art style and technical constraints, will help determine how accurate the model and textures need to be.

Objectives for this project are relatively straightforward: Since the asset will be used in a simulation the model and textures will need to look fairly realistic. It will also fill the screen when the player is reading the dial and sighting landmarks but the model and textures will need to be optimized to fit within allotted resource footprint. The ideal poly budget is between 10,000-12,000 triangles with a maximum of two materials. One set of textures for transparent materials and the other for opaque materials. Dimensional accuracy is also important because the linear graduation marks on the side of the base can be used to measure distance on in-game maps.

The accuracy of a model's details tends to be limited by the quality of the reference material. Physical access, scan data and detailed drawings are ideal reference sources for real objects. These types of references can be measured directly and that makes it a lot easier to establish real world scale. Which helps create a model with accurate proportions. Photographs and illustrations can also be used as references but require a bit more effort to use effectively. Collect, compare, cross check and cull the reference images until there's a set that accurately represents the subject.

Reference images of key angles (Top, front, side, etc.) can be aligned and overlapped to create a reference sheet. The object's overall dimensions can then be used to estimate the size of key features on the reference sheet. Following the reference sheet while also using these dimensions and incremental snapping (In real world units.) should produce a model that's built close to scale with fairly accurate proportions.

Obscure topics tend to be more difficult to research but there's usually a lot of usable reference material for most objects. It's often helpful to start the search with broad terms then refine the keywords as the terminology used to describe the components becomes more familiar. Collector or enthusiast communities can be great resources for reference material and specialized information. Locating useful reference sources just takes a bit of effort and persistent searching.

A few quick tests with primitive shapes can be used to evaluate the optimal number of segments for the low poly model and verify the dimensional accuracy of key features. Small scale samples like this can be used to identify potential issues, isolate specific variables and test different solutions. The simplicity of these test models also makes it a lot easier to resolve proportion and topology issues with the major forms, without having to invest a significant amount of time.

The initial block out just establishes the overall scale and proportions of the basic shapes. These shapes are then used as a base for the detailed block out. Individual features are added to the model in a series of iterative detail passes. Boolean operations are used to join the individual mesh components and modifiers are used to generate precise curves, bevels and copies of repetitive shapes. This helps keep the individual mesh components fairly simple. Which makes it a lot easier to make major changes without having to manually re-work large sections of the model.

Both halves of the model were blocked out at the same time. It's just easier to show progress on each half separately.

The first couple of detail passes are focused solely on blocking out the larger components. Smaller details will be added in subsequent passes. Deciding which details get added to a specific stage of the block out comes down to two basic factors: context and consistency. Context means looking at decisions in relative terms that relate to things like scale, in-game usage, workflow, etc. Consistency means looking at the overall goals for the project and previous decisions then applying the same logic in a uniform way.

E.g. adding all of the text to the base mesh would easily push the model beyond the resource budget for the low poly but adding the linear gradation marks may be necessary to increase the accuracy of the map readings. Especially for users with lower end systems that can't display textures at full resolution. This is where using modifiers to generate certain features provides a lot of flexibility that hedges future change requests.

Updating complex details or toggling them on and off with the modifier stack means that both the high poly and low poly models can be generated from the same base mesh. Which can help streamline a lot of the high poly to low poly workflow and allows for a more pragmatic approach towards high poly modeling. This block out strategy is generally compatible with both subdivision modeling and boolean re-meshing workflows.

E.g. there's a lot of text and repetitive surface details on the larger components and it's easier to run those parts through a boolean re-meshing and polishing workflow in ZBrush. The rest of the smaller components are fairly simple shapes. So, it makes more sense to use a subdivision modeling workflow with a mix of floating and solid geometry to create those parts.

It's also important to keep things organized. Logical and consistent naming conventions will make it easier to locate files. Notes with the settings used for different modeling operations, like the various re-meshing and polishing steps, will make it easier to update the model after making changes. General process notes will also be helpful for handing off project files or when revising a project that needs adjustments 6-12 months down the road.

Below is a visual outline of the basic workflow for this asset and a brief description of the modeling techniques used during each stage of the process.

• Block out: basic poly modeling with numerous booleans and modifiers.
• Base model: poly modeling with modifiers for edge bevels and round overs.
• High poly model: re-meshing with edge polishing pass and basic subdivision with modifiers.
• Low poly model: basic poly modeling.

Certain parts of this workflow could have been simplified further. Mainly the high poly re-meshing and polishing but trading a small increase in speed just isn't worth the reduced flexibility. The primary advantage of this workflow is only having to build the base mesh once and being able to use that one mesh to generate both the high poly and low poly model. Which makes it a lot easier to push any last minute changes through without having to do a lot of re-work.

Low poly optimization is pretty straightforward: turn off the modifiers used to generate the edge and surface details. Setup the mesh smoothing groups then unwrap and pack the UVs. Adjust the split placement and re-pack as needed to maximize the quality. Run several test bakes before accepting a layout.

Hard edges [edge splits] are placed to control the smoothing behavior on the low poly. If the mesh shading and normal bakes look good then it's generally acceptable to have larger smoothing groups and some gradation in the normal map. Each new UV island increases the amount of texture space lost to padding. So, unnecessary hard edges effectively reduce the overall textel density of a model.

UV splits can be placed at the same time to back the hard edges and control the UV unwrap. Hiding splits and seams along the natural breaks in the shapes can help reduce the visibility of any minor artifacts that may appear along the split edges. It may also be necessary to adjust the scale of the UV islands, based on their distance from the players camera, to optimize the textel density for the mesh's size on screen and visibility. The goal here is to use an appropriate number of seams, placed in a way that balances straightening the UVs with minimizing any noticeable distortion and limiting the total number of UV islands.

In the end, adding the linear graduation marks and lettering with texture masks would have simplified the high poly process. The base model could have just been left blank and used to create a subdivision high poly where the edge loops are generated with a bevel / chamfer modifier. Once again, the tradeoff in time saved just wasn't worth the headache of solving potential accuracy issues with the linear graduation marks and this would have also made it extremely difficult to pivot to a fully modeled low poly if the project required it.

Alternately: a full sculpt pass could have been done on the high poly model but much of the damage was fairly shallow. So it made more sense to just paint the texture masks and use the height values to generate the changes in the normal maps. This also made it easier to gradually reveal the different layers in the materials and turn specific types of damage on or off based on the different wear states. Much faster than manually sculpting these details.

Some additional write-ups on related topics:

Block outs and incremental progression.

https://polycount.com/discussion/comment/2751240/#Comment_2751240

Mesh complexity and shape accuracy

https://polycount.com/discussion/comment/2751340/#Comment_2751340

Isolating variables and iterating to solve complex problems.

https://polycount.com/discussion/comment/2760744/#Comment_2760744