UVPackmaster supports packing to UDIM tiles in the following packing modes:

Packing mode Tiles

Packing mode set to Tiles

In this mode packer will pack selected islands into the number of consecutive UDIM tiles specified by the user using the Tile Count parameter. Behavior of this mode varies greatly depending on whether the Fixed Scale option is enabled.

Fixed Scale on

If Fixed Scale is on, then packer will not scale islands during packing. If there is no room to pack an island in the current tile, it will be packed into the next tile. Packer will return an error if the islands can’t fit into the specified number of tiles. Packing will also fail if the UV map contains an island larger than a single tile.

A UV map packed to 4 tiles without scaling (hence the unused area in the last tile)

Fixed Scale off

If Fixed Scale is off, then packer will scale the selected islands, so they fit into the specified number of tiles, minimizing the unused area. Keep in mind that the applied scale will be the same for every island, so proportions between islands don’t change after packing.

A UV map packed to 4 tiles with adjusted scale to minimize the unused area

If the Tile Count parameter is set to 0, then the number of tiles used during packing is unlimited.

Tiles filling limitations

A usual UV map can be packed so it properly fills almost every number of tiles. There are rare cases though, when a given UV map cannot be fit into a specific number of tiles to a great extent, even with scaling enabled. This might be the case for example, when the UV map contains one island which is much bigger than other islands. In such scenario the maximal scale, which might be applied to islands is limited by the size of the biggest island (the island must fit into a single tile). The same limit will also apply to the smaller islands (because scaling is always uniform across the UV map). In result, the smaller islands might not cover the requested number of tiles. In such situation packer will scale the islands up during packing, so they cover as much area as possible, but there still will be a large part of unused area in the tiles. In order to mitigate this issue, the user should adjust the UV map so the proportions between islands are more uniform.

Packing mode Groups To Tiles

Packing mode set to Groups To Tiles

In this mode the UV islands are split into many groups using a grouping method chosen by the user. Every group will be packed separately info its own tile.

Grouping methods available:

  • material
  • object
  • mesh part
  • similarity
  • manual

Keep in mind that packer will apply different scaling to every group during packing, so that islands belonging to a given group fit into a given tile. It means that while the proportions between islands belonging to the same group will be the same after packing, the proportions between islands belonging to different groups will change.

Groups To Tiles mode: every group was packed to its own tile

Manual grouping

When selecting the grouping method, the user specifies the way the islands will be split into groups, but in case of most of the methods, he cannot control the order of the groups, i.e. which group comes as first, which group as second etc. In context of the Groups To Tiles packing mode, it means that the user cannot specify which group will be packed into which tile.

To solve this issue a special Manual grouping method was introduced. With this method the user can assign a group number to every island. He can do it in the Manual Grouping panel. Islands sharing the same group number will be processed by the packer as belonging to the same group. An advantage of manual method comes from the fact, that group numbers also determine the order of the groups. It means that a group specified by number 0 will always be the first group, and it always will be packed into the first tile when using the Groups To Tiles packing mode. The group number 1 will always be packed into the second tile etc.

Manual Grouping panel

The user can assign numbers arbitrary, according to his needs. In particular he may skip some numbers, for example he may define the group number 0 and group number 2, omitting the group number 1. In such a case, the second tile will be left empty during packing, only the first and the third tile will be used.

WARNING: keep in mind that the greater the group number, the farther from the UV origin its tile will be located when using Groups To Tiles packing mode.

Manual group numbers shown by the add-on. Group number 1 not used - hence the empty tile

Packing to tiles with a custom packing box

When packing to tiles with a custom packing box enabled, then the packing box defines the position and dimensions of the first tile. Other tiles follow the first tile accordingly.