# CAD-to-USD Conversion Advisor > CAD conversion is a pre-USD concern; `omniverse-usd-performance-tuning` cites this reference when the user reports `problem_type = conversion quality`. --- Use this reference for CAD import, tessellation, conversion specs, or conversion-quality problems. ## Purpose Guide CAD-to-USD conversion diagnosis before optimization. Capture the source format, converter/runtime, conversion spec, tessellation behavior, and post-conversion validation handoff. ## Prerequisites - A CAD source format or converted USD path. - Converter name, version, and runtime when available. - The supplied conversion spec, generated GUI config, or a note that no spec is available. ## Examples - "Advise conversion settings for a STEP file with faceted curved surfaces." - "Review this converter spec before I optimize the exported USD." ## Checklist - Identify source format. - Capture converter version and runtime. - Capture the exact conversion spec or generated GUI config. - Identify whether geometry is being tessellated by the converter or read as already-tessellated source data. - Validate the converted USD before optimization (route through `usd-validation-runner`). - Route post-conversion performance issues through composition audit (now part of `usd-structure-assessment`) and validation. ## Known caveats - Converter spec files may vary by converter backend. - GUI controls can map to generated JSON config rather than a directly supplied spec. - Some formats may contain already-tessellated mesh data, so a tessellation LOD knob may not improve faceting. - Surface tolerance and tessellation controls can be backend-specific. ## Limitations - Does not execute conversion or Scene Optimizer operations. - Cannot guarantee a tessellation knob exists for every source format or backend. - Post-conversion performance issues still need composition audit and validation. ## Troubleshooting - If tessellation settings have no visible effect, check whether the source is already tessellated mesh data. - If GUI and CLI settings disagree, capture the generated JSON/config file and map it back to converter controls. - If the converted stage performs poorly, route through composition audit (`usd-structure-assessment`) and validation (`usd-validation-runner`) before optimization. ## Output Capture conversion inputs and conclusions in the optimization plan under `inputs.converter`.