Dllu

This is the userpage of dllu. I work on robotics. I enjoy programming, 2D vector graphics, 3D graphics, physics, and photography.

• 2008—2014 Bachelor of Applied Science, Engineering Physics at the University of British Columbia.
• 2014—2016 Master of Science, Robotics at Carnegie Mellon University.
• 2016—2020 Software Engineer, 3D mapping at Ouster, a manufacturer of automotive lidar.
• 2020-2021 Staff Software Engineer, Tempus Ex Machina, a startup
• 2021-2023 Senior Software Engineer, Tesla
• 2023-present Software Engineer, Main Street Autonomy

I contribute mostly to articles related to computing, robotics, geometry, and various niche topics, although I sometimes contribute photos to other articles. Please feel free to add things to the articles listed below or post any questions to my talk page.

Articles I've contributed significantly to

• Biham-Middleton-Levine traffic model (created)
• Swinging Atwood's Machine (greatly expanded)
• Monte Carlo localization (rewritten)
• Point set registration (created)
• Visibility polygon (expanded)
• Phipps Conservatory and Botanical Gardens (expanded)

Smaller articles I've contributed to

• Tair (lens) (created)

Featured Pictures

Pittsburgh

Sony a7R, Sony Zeiss Sonnar T* FE 55mm f/1.8 ZA

Organic Molecules Render

Created with Rhinoceros 3D and VRay.

BML Traffic Model

Main page: User:dllu/BML

A globally jammed phase with a traffic density of 60%.

A free flowing phase with a traffic density of 28%.

A periodic intermediate phase with a traffic density of 38%.

A disordered intermediate phase with a traffic density of 39%.

Maze generation

Main page: User:dllu/Maze

30x20 "backtracking" maze generation.

30x20 "prim" maze generation.

Arbitrary selection of other diagrams I've made

Coherent point drift

These were made with the reference implementation of coherent point drift by Myronenko and Song.

Affine point set registration without noise.

Rigid point set registration with noise.

Non-rigid point set registration with noise.

Orbits of the Swinging Atwood's Machine

Type A orbits of the Swinging Atwood's machine.

Type B orbits of the Swinging Atwood's machine.

The following family of diagrams are generated by my C++ code, which can be found at [1].

Orbit with mu = 3 starting from rest.

Orbit with mu = 5 starting from rest.

Orbit with mu = 16 starting from rest.

Orbit with mu = 20 starting from rest.

Monte Carlo localization

I see a door.

I don't see a door.

A robot using Monte Carlo localization to determine its position in a one-dimensional circular corridor containing three doors, using only a sensor that detects whether or not there is a door. The vertical grey bars at the bottom are the locations of the particles which represent the robot's current belief of its position. More particles clustered together means the robot is more likely to be there.

The following family of diagrams are generated by my C++ code, which can be found at [2].

1. Initialization.

2. Sensor update.

3. Resampling.

4. Motion update.

5. Sensor update.

6. Resampling.

7. Motion update.

8. Sensor update.

9. Resampling.

Photography

Current gear

Camera

• Alkeria Necta N4K2-7C
• Fujifilm GFX100S

Lenses

• Fujifilm G-mount lenses 23mm f/4, 50mm f/3.5, 55mm f/1.7
• Cosina Voigtländer APO-Lanthar 90mm f/3.5 SL (M42 mount) and 125mm f/2.5 (F mount)
• Leica Apo-Telyt-R 180mm f/3.4 (R mount, adapted)
• Sigma Art 70mm f/2.8 Macro (EF mount)
• Cosina Voigtländer Apo Skopar 90mm f/2.8 (F mount)

Retired gear

• Kowa 3.5mm f/2.4 (C mount)
• Tokina FIRIN 20mm f/2 FE MF (FE mount)
• Cosina Voigtländer Nokton 50mm f/1.5 Asph. VM (M mount)
• Myutron FV5026W 50mm f/2.6 (F mount)
• Cosina Voigtländer Nokton 58mm f/1.4 (F mount)
• Cosina Voigtländer APO-Lanthar 65mm f/2 (FE mount)
• Cosina Voigtländer Heliar Classic 75mm f/1.8 VM (M mount)
• Sony FE 70-300mm F4.5-5.6 G OSS (FE mount)
• MS-Optics Aporis 135mm f/2.4 (M mount)
• Samyang 135mm T2.2 (F mount)
• Mamiya Apo-Sekor Z 350mm f/5.6 (RB/RZ mount)
• Canon FD 500mm f/4.5 L (FD mount)
• Tamron 17-50mm f/2.8 VC (EF mount)
• Canon EF 85mm f/1.8 USM (EF mount)
• Cosina Voigtländer Super Wide Heliar III 15mm f/4.5 Asph. VM (M mount)
• Sony FE 28mm f/2 (FE mount)
• Sony Carl Zeiss Sonnar T* FE 55mm F1.8 ZA (FE mount)
• Tair 11a 135mm f/2.8 (M42 mount)
• Mamiya Apo 200mm f/2.8 for 645 mount
• Micro-Nikkor 60mm f/2.8D AF
• Fujifilm G-mount lenses 45mm f/2.8, 80mm f/1.7

• Sony a7R
• Sony a7R II
• Canon EOS Rebel XS
• Fujifilm GFX 50R

• 
  1390 Market Street, San Francisco, CA
• 
  Airstream trailer, Joshua Tree, CA
• 
  Apple Park, Cupertino, CA
• 
  Golden Gate Bridge, San Francisco, CA
• 
  Centerm, Vancouver, BC
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  Market at Third, San Francisco, CA
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  Duquesne Incline, Pittsburgh, PA
• 
  Ferry Building, San Francisco, CA
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  Golden Gate Bridge, San Francisco, CA
• 
  Heinz Memorial Chapel, Pittsburgh, PA
• 
  Capitol Hill, Seattle, WA
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  Hillman Library, Pittsburgh, PA
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  Phipps Conservatory, Pittsburgh, PA
• 
  Pittsburgh, PA
• 
  Pittsburgh, PA
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  Garbage Truck, San Francisco, CA
• 
  Jintai Temple, Zhuhai, China
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  Bay Bridge, San Francisco, CA
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  City Hall, San Francisco, CA
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  City Hall, San Francisco, CA
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  Transamerica Pyramid, San Francisco, CA
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  Union Square, San Francisco, CA
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  Fisher Girl, Zhuhai, China