image-to-skm — Convert Images to SketchUp Material (.skm) Files

Convert JPG, PNG, BMP, GIF, TIFF, and WebP images to SketchUp's .skm material format. No SketchUp license required.

What is an SKM file?

SketchUp uses .skm files to store materials (textures + metadata). An .skm file is a ZIP archive containing:

material.skm
├── document.xml            ← material definition (color, texture scale, name)
├── documentProperties.xml  ← metadata (creator, timestamps)
├── references.xml          ← schema references
├── doc_thumbnail.png       ← 128×128 preview thumbnail
└── ref/
    └── texture_1.jpg       ← the texture image

The XML format uses SketchUp's http://sketchup.google.com/schemas/sketchup/1.0/material namespace. Each material stores:

• Average color (colorRed, colorGreen, colorBlue) — computed from the image pixels
• Packed BGR integer (avgColor) — blue*65536 + green*256 + red
• Texture scale (xScale, yScale) — real-world tile size in inches (independent width/height)
• Texture reference — the image stored under ref/ with an _1 id suffix

This format was reverse-engineered from real .skm files shipped with SketchUp 2026. It is compatible with SketchUp 2017 and later.

Why does this exist?

SketchUp doesn't provide a way to batch-create materials from image files. If you have texture images (wood grain, tile, fabric, etc.), the only official way to make them into .skm files is to open SketchUp, create a material manually, apply the texture, and save it. For one image that's fine — for dozens it's tedious.

This tool automates it: give it images, get .skm files you can import directly into SketchUp's Materials panel.

Supported input formats

Format	Extensions
JPEG	.jpg, .jpeg
PNG	.png
BMP	.bmp
TIFF	.tif, .tiff
WebP	.webp
GIF	.gif

Installation

Requirements

• Python 3.10+ (macOS, Linux, Windows)
• Pillow — for image processing (average color, thumbnail generation)

pip install Pillow

macOS GUI app (optional)

To build the native macOS app with image preview and batch conversion:

pip install py2app pyobjc-framework-Cocoa
python build_app.py

This creates SKP Converter.app on your Desktop — double-click to launch.

Usage

macOS GUI app

The app provides a complete interface for converting images to SKM:

1. Add images — click "Add Files…" to select one or more images
2. Set material name — optionally enter a custom name
   • Leave blank to use each image's original filename
   • With multiple images, a custom name produces Name-1.skm, Name-2.skm, etc.
   • With a single image, the name is used as-is: Name.skm
3. Choose output folder — same folder as source, or pick a custom destination
4. Set tile size — pick a preset or enter custom width × height
   • Units dropdown: choose between inches (in), centimetres (cm), feet (ft), or metres (m)
   • Switching units auto-converts the displayed values
   • Presets include common sizes: 1m×1m, 5ft×8ft, 8ft×10ft, etc.
5. Preview — shows the selected image scaled to your chosen tile proportions
6. Click Convert
7. Reveal in Finder — after conversion, click to open the output folder directly

Settings (unit, dimensions, output folder) are remembered between sessions.

Command line

Convert a single image (default 1m × 1m tile):

python img_to_skm.py photo.jpg
# → photo.skm (in same directory)

Convert multiple images with custom scale:

python img_to_skm.py *.jpg --scale 24
# → each .skm at 24" × 24" (2 ft square)

The --scale flag sets both width and height in inches. For independent width/height, use the Python API or GUI app.

Python API

import img_to_skm

# Square tile (1 metre = 39.37 inches)
img_to_skm.convert("brick.jpg", scale=39.37)

# Rectangular — 5 ft wide × 8 ft tall (e.g., a rug)
img_to_skm.convert("rug.jpg", x_scale=60, y_scale=96)

# Custom output directory and material name
img_to_skm.convert("tile.png", scale=12, output_dir="/path/to/materials", material_name="My Tile")

Importing into SketchUp

SketchUp for Web (free online version)

1. Open the Materials panel by clicking the materials icon in the right sidebar
2. Click the Upload button (arrow pointing up)
3. In the "Choose Material" popup, click My device or drag and drop your .skm file
4. The material is added and ready to paint onto faces

SketchUp Desktop (Pro / Studio)

1. Open the Materials panel (Window → Materials on Mac, or Default Tray on Windows)
2. Click the Details menu (gear icon) → Add Collection to Favorites…
3. Select the folder containing your .skm files
4. The materials appear in the panel, ready to paint onto faces

Alternatively, use File → Import and select a .skm file directly.

Common scale values

Real-world size	Inches	Centimetres	Use case
0.5 m × 0.5 m	19.69 × 19.69	50 × 50	Small tiles
1 m × 1 m	39.37 × 39.37	100 × 100	Standard tiles, wood planks
2 m × 2 m	78.74 × 78.74	200 × 200	Large wall panels
1 ft × 1 ft	12 × 12	30.48 × 30.48	Floor tiles
2 ft × 3 ft	24 × 36	60.96 × 91.44	Small rugs
5 ft × 8 ft	60 × 96	152.4 × 243.8	Area rugs
8 ft × 10 ft	96 × 120	243.8 × 304.8	Large area rugs

File format reference

document.xml

<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<materialDocument
  xmlns="http://sketchup.google.com/schemas/sketchup/1.0/material"
  xmlns:mat="http://sketchup.google.com/schemas/sketchup/1.0/material"
  xmlns:r="http://sketchup.google.com/schemas/1.0/references"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://sketchup.google.com/schemas/sketchup/1.0/material
    http://sketchup.google.com/schemas/sketchup/1.0/material.xsd">
  <mat:material name="MaterialName" type="1" workflow="0"
    colorRed="135" colorGreen="103" colorBlue="96"
    colorizeType="0" trans="0" useTrans="0" hasTexture="1">
    <mat:texture textureFilename="image.jpg"
      xScale="39.370100" yScale="39.370100" avgColor="6317959">
      <mat:images>
        <mat:image id="1" path="image_1.jpg" file_name="image.jpg" />
      </mat:images>
    </mat:texture>
  </mat:material>
</materialDocument>

Key fields:

Field	Type	Description
name	string	Material name (displayed in SketchUp)
type	int	Always 1 for textured materials
workflow	int	0 = basic, 1 = PBR (physically based rendering)
colorRed/Green/Blue	int 0–255	Average color of the texture
colorizeType	int	0 = none
trans	float	Transparency (0 = opaque)
useTrans	int	0 = no transparency
hasTexture	int	1 = has texture image
textureFilename	string	Original image filename
xScale / yScale	float	Tile size in inches (39.37 ≈ 1 metre)
avgColor	int	Packed BGR: (blue << 16) | (green << 8) | red
path	string	Internal filename with _<id> suffix
file_name	string	Original filename

documentProperties.xml

Metadata — title, timestamps, revision number. The generator element should be Material version 1.

references.xml

Empty self-closing element with the references namespace. No external references are needed for basic materials.

Texture storage

Texture images are stored inside the ZIP under ref/. The filename gets an _<id> suffix inserted before the extension:

• photo.jpg → stored as ref/photo_1.jpg
• tile.png → stored as ref/tile_1.png

PBR materials (workflow="1")

SketchUp 2025+ supports PBR materials with additional texture maps (roughness, normal, ambient occlusion). These use workflow="1" and add a <mat:pbrMR> element. This tool generates workflow="0" (basic) materials which are compatible with all SketchUp versions from 2017 onward.

How it was built

The .skm format is not publicly documented by Trimble. This tool was built by reverse-engineering real .skm files from SketchUp 2026's shipped materials library. The XML structure, namespace URIs, and attribute semantics were determined by inspecting files like Tile Mosaic Multi.skm and Plywood_01_1K.skm.

Project structure

image-to-skm/
├── img_to_skm.py      ← core converter (CLI + Python API)
├── converter_app.py    ← macOS GUI app (tkinter)
├── build_app.py        ← builds SKP Converter.app using py2app
├── setup.py            ← py2app configuration
├── README.md
└── LICENSE             ← MIT

License

MIT