Introduction

The 3DTG tool will process textured 3D meshes (and soon point clouds) and convert them into the Cesium 3D Tiles standard used for streaming large datasets on the web. Also see 3D Tiles Overview

Build dependencies

make, cmake and g++ commands should be available on your OS. Also, posix threads should be available for the C++ compiler.

1. make command can be provided through the GNU Make
2. cmake command can be provided through the CMake

Win

1. make command can be provided through the GNU Make
2. cmake command can be provided through the CMake
3. g++ command can be provided through the MinGW

During the MinGW installation posix should be selected as a threads module.

MacOS

1. make command can be provided through the brew install make
2. cmake command can be provided through the brew install cmake
3. g++ command should be available after XCode is installed or throught the brew install gcc

Linux

1. make command can be provided through the brew install make
2. cmake command can be provided through the both a apt install cmake or a brew install cmake
3. g++ command can be provided through the apt-get install g++-version

Build

1. Build all the dependencies through the appropriate batch file (depsWin.bat or depsUnix.sh depending on your OS) from root folder of the project.
2. Build main app by running make or by entering into "build/" subfolder and running from there cmake ..

CLI Options

Command	Reuired	Initial value	Description
-h, --help	No		List all of the available commands for the current program version.
-i, --input	Yes ✅		Input model path
-o, --output	No	./exported	Output directory
-l, --limit	No	2048	Polygons limit (only for Voxel, Regular split alorithms)
-g, --grid	No	64	Grid resolution (only for Voxel algorithm)
--iso	No		Currently unused
-a, --algorithm	No	voxel	Split algorithm to use
--algorithms	No		Available algorithms list
-f, --format	No	b3dm	Model format to export
--formats	No		Available formats list
--compress	No		Enables Draco compressing
--texlevels	No	8	Number of texture LOD levels (0 - disables texture LOD generation)

-h, --help

Prints an application help message into the CLI.

-i, --input (required)

Input model path

Example

3dtg -i ./someFolder/myModel.obj

This option can be used in a positional way as a first argument

3dtg ./someFolder/myModel.obj

-o, --output

Output directory path

Example

3dtg ./someFolder/myModel.obj -o ./outdir

This option can be used in a positional way as a second argument

3dtg ./someFolder/myModel.obj ./outdir

-l, --limit

Polygons limit until model will be split

Example

3dtg ./someFolder/myModel.obj ./outdir -l 4096

-g, --grid

Grid size that is used to decimate voxelized meshes.

Grid example

Should be set as a single value. The higher is value the higher is the output resolution.

Default value is 64 which means [x, y, z] => [64, 64, 64]

Example

3dtg ./someFolder/myModel.obj ./outdir -g 32

-a, --algorithm

Algorithm to use to split mesh

Default value is voxel

Example

3dtg ./someFolder/myModel.obj ./outdir -a regular

-f, --format

Model format to use to save models

Default value is b3dm

Example

3dtg ./someFolder/myModel.obj ./outdir -f glb

--compress

Enables Draco compression

Example

3dtg ./someFolder/myModel.obj ./outdir --compress

--texlevels

Texture LOD levels count

Pass 0 if you want to disable texture LOD generation.

Default value is 8

Example

3dtg ./someFolder/myModel.obj ./outdir --texlevels 4

Functionality

Current Functionality

Currently the tool only accepts textured OBJ files, and simplifies the geometry using a voxel decimation algorithm. The output is a 3d tiles.

Syntax:
3dtg.exe -i path\to\input\obj -o path\to\3d-tile\folder

Memory usage

A rough estimate of memory usage can be calculated by adding up the number of textures and the size of the uncompressed 3d mesh. 16k textures use about 1GB ram 8k textures use about 0.25 GB of ram (256MB) 4k textures use about 0.06 GB ram (64MB)

System ram usage = (Mesh_in_OBJ_format) + (#_of_textures * Texture_Resolution)

This will provide a rough ballpark on the amount of system ram required for processing your textured mesh.

Future Improvements

This is a list (in no particular order) of improvements that can be made:

• Caching mechanism (C++ equivalent to Caffeine caching in Java)
• alternate decimation/simplification algorithms
• alternate texture baking/transfer algorithms in the creation of LODs
• Optomizations for increased processing performance
• GPU acceleration for faster overall processing
• Multiple input file formats (FBX, DAE/ZAE, GLTF/GLB)
• KTX 2.0 Basis texture encoding for better texture compression (better then jpg)
• Support point clouds (las/laz, e57 and other formats)
• add your own!

Dependencies

• GLTF : GLTF structures for encoding/decoding both a GLTF and a B3DM.
• draco : Draco compression lib for GLTF compression.
• rapidjson : JSON generation, used internally in GLTF lib to generate GLTF models.
• json : JSON generation, used primarily.
• stb/images : Image module for encoding/decoding various image data formats.
• cxxopts : CLI options parser.
• glm : Math library for graphics.