# STL Transformation

OrcaSlicer primarily relies on STL meshes for slicing, but STL files may come with several limitations.

Typically, STL files feature a low polygon count, which can adversely affect print quality.
In contrast, using STEP files offers a higher-quality mesh that more accurately represents the original design. However, be aware that both high-polygon STL and STEP files can increase slicing time.

![image](./images/stl%20transformation/stl-transformation-smooth-rough.png)

## Importing STEP files

This setting determines how STEP files are converted into STL files and is displayed during the STEP file import process.

If you don't see this when opening a STEP file, check [Don't show again](#Don't-show-again) below.

![image](./images/stl%20transformation/stl-transformation.png)

### Parameters:

The transformation uses [Linear Deflection and Angular Deflection](https://dev.opencascade.org/doc/overview/html/occt_user_guides__mesh.html) parameters to control the mesh quality.
A finer mesh will result in a more accurate representation of the original surface, but it will also increase the file size and processing time.

![image](./images/stl%20transformation/stl-transformation-params.png)

- **Linear Deflection**: Specifies the maximum distance allowed between the original surface and its polygonal approximation. Lower values produce a mesh that more accurately follows the original curvature.
- **Angular Deflection**: Defines the maximum allowable angle difference between the actual surface and its tessellated counterpart. Smaller angular deflection values yield a more precise mesh.

#### Split compound and compsolid into multiple objects:

Enabling this option will split the imported 3D file into separate objects. This is especially useful for adjusting individual object positions, tweaking print settings, or optimizing the model through simplification.

![image](./images/stl%20transformation/stl-transformation-split.png)

#### Don't show again

This option will hide the STL transformation dialog when opening a STEP file.
To restore the dialog, go to "Preferences" (Ctrl + P) > "Show the STEP mesh parameter setting dialog".

![image](./images/stl%20transformation/stl-transformation-enable.png)

## Simplify model

When working with models that have a high polygon count, the Simplify Model option can significantly reduce complexity and help decrease slicing times.

This function is especially useful for improving the performance of the slicer or achieving a specific faceted look for artistic or technical reasons.

To access the Simplify Model option, right-click on the object to simplify in the "Prepare" menu.

![image](./images/stl%20transformation/simplify-menu.png)

It is recommended to enable the "Show Wireframe" option when running a simplification process to visually inspect the outcome. However, be cautious: overly aggressive simplification may lead to noticeable detail loss, increased ringing, or other printing issues.

### You can Simplify your model using the following options:

- **Detail Level:** Control the level of detail in the simplified model by choosing from five preset options. This setting allows for a balance between mesh fidelity and performance.
- **Decimate Ratio:** Adjust the ratio between the original model's polygon count and that of the simplified model. For instance, a decimate ratio of 0.5 will yield a model with approximately half the original number of polygons.