Unwrap UV Overview and Guidelines

Started by DriesV, January 06, 2020, 10:26:41 AM

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KeyShot 9.1 introduces a new Unwrap UV Geometry Tool for UV unwrapping of model meshes.

The Unwrap UV Tool allows to create geometry-specific texture projections. This allows users to texture models with deformed plywood, braided cables etc. with proper texture flow and without distortion.

Access Unwrap UV Tool

The UV unwrapping functionality can be accessed through the newly added 'Unwrap UV' Geometry Tool. The tool can be accessed through the Tools selection in the Ribbon or by right-clicking on a part in the Real-time View.

Unwrap UV terminology

  • Chart: "Island" of connected triangles that is projected in UV space when unwrapping.
  • Seam: Seams define boundaries between separate Charts. They are created automatically when creating adjoining Charts. Seams are also necessary to successfully unwrap shapes like cylinders. A seam can be thought of as a cut into a chart.
  • Direction Guide: A manually drawn path that guides the flow of the texture.

UI Overview

Quick Unwrap
Single-click unwrapping that automatically unwraps the geometry as a single chart.

Unwrap Shell
This mode works best for shell-like model topologies that are surface sheets and non-solids.

Advanced Unwrap
Manual unwrapping with explicit control over seam and chart creation.

Add Seam
Clicking 'Add Seam' starts a vertex selection mode. A seam path can be created by clicking on subsequent vertices. Click the green check mark to accept the seam. Click the red cross to discard it. Seams have a red color.
Tip: When drawing a seam by picking vertices, a path suggestion is shown as a dashed line. Clicking near a vertex along the dashed line extends the seam up to that vertex. Double clicking at the last selected vertex extends the seam as far as possible.

Use as Direction Guide
If this option is enabled while the 'Add Seam' mode is active, the drawn seam will also act as a texture flow direction guide. Direction Guide Seams have an orange color. Note: this option needs to be enabled before clicking the first vertex.

Add Charts
Charts can be selected in various ways, depending on model topology or complexity. The 'By Angle' mode is active by default.

By Existing Chart
This mode allows to select charts according to the existing UV layout. For CAD models, the charts are defined by the original NURBS patches/surfaces.

Flood Fill
Adds a single chart that is grown from the point that is clicked across the entire geometry.

By Angle
Charts are created according to the relative angle between the selected and adjacent triangles. The Angle slider works as a threshold for selection. A lower Angle will decrease the selection scope.

Extend Chart
This option allows to extend selected charts by clicking on directly adjacent triangles.

Set Direction Guide
Direction Guides are defined in the same way as seams, i.e. by picking vertices. Two or more direction paths should roughly have the same direction and should not cross each other. Direction Guides of equal length give the best results. Direction Guides have a green color.
Tip: When drawing a direction guide by picking vertices, a path suggestion is shown as a dashed line. Clicking near a vertex along the dashed line extends the direction guide up to that vertex. Double clicking at the last selected vertex extends the direction guide as far as possible.

Click to unwrap the geometry according to the specified charts and seams. This button becomes available when at least one chart has been specified. If part of the geometry is not covered by charts, then the remaining faces can be auto-filled onto charts.

Position Charts
After a model has been unwrapped, the charts can be manipulated. These sliders allow to transform the unwrapped charts. Pick a chart in the viewport to apply transforms to it.

Base UV Size
Sets the size of the [0,1] range in the unwrapped UV space. For consistent texture scale across multiple unwrapped models, this value should be kept constant.

Scale the picked chart.

Rotate the picked chart.

Use Material Texture on UV Regions
Displays the diffuse material texture in the Unwrap UV viewport. This is enabled by default when a texture has been applied. This option currently only works for image textures. When this option is unchecked, the default color-coded [a0, j9] UV preview is shown.

Limitations & Known Issues

  • Individual Charts, Seams and/or Direction Guides currently cannot be deleted.
  • Unwrapping models with over 500k triangles may be (very) slow at the moment.

If you have any other questions, simply reply or email us at beta@luxion.com.

Happy unwrapping!

The Luxion team


Hi Dries.
I will be great if we can see a quick tip on video.
Thanks a lot.