Gryphon Scan

This is highly customizible version of Horus 3D Scan software with some advanced features support

This project was created to support custom built Ciclop-style 3D scanners with different hardware configurations and some more features like:

• photo lights control
• saving photos for photogrammetry
• enchanced calibration
• etc...

Also to enhance the existing functions and to fix bugs.

For the people who expect software with the single "Make Cool Scan" button

Sorry guys. This is DIY project not the finished commercial software. If you are not ready for some manual install and adjustments than please don't waste your time.
This project need a bit of understanding how things are work. Here can be some bug's. This is platform for learning and experiments.

I will try to make things work smooth but i can not warranty everything will work out of the box in every environment. Most likely you'll need to spend some time and use brain to make things work.

Please don't write that shitty comments as you do for Ciclop/Horus. This is not the out of the box solution at the moment.

Dear Visitors

I need some feedback for this project including usage (beta testing) experience. Also please point me to the right place where Ciclop/Horus based scanners are discussed at the moment as there is completely no activity on the original Ciclop/Horus repositories. Is there any 3D scanner project that superseeds Horus?

At the moment:

• customizible camera height/angle/distance
• support for autofocus cameras in calibration->video panel (camera driver has to support set focus), autodetect camera resolution
• customizible scan area (turntable) size
• photo lights control support at laser pins 3 and 4 (be aware that board hardware pins current is limited and you need extra hardware for powerful lights)
• fixed turntable firmware hello string detection (horus-fw 2.0 support or any custom grbl based firmwares if same G-codes are supported)
• save frames for Photogrammetry
• enhanced calibration:
  • augmented visualization allow visually check calibration quality both for platform and lasers
  • augmented laser lines draw over pattern allow to manually move pattern and compare actual laser beam and calibrated
  • better pattern usage in laser calibration
  • draw trace of detected laser lines during laser triangulation
  • multipass calibration mode for laser triangulation to increase accuracy
  • more informative calibration directions pages
  • reworked platform calibration
  • save/read camera calibration frames (autosave to 'camera_intrisics' folder. read with 'r' button in "Camera Intrinsics")
• HSV laser line detection method, Green and Blue laser colors support
• experimental "Laser background" filter to remove laser line detected at background objects
• laser id saved as "Original_cloud_index" field at .ply export so point cloud can be separated by lasers and additionally aligned
• some builtin constant values moved to settings or estimated automatically
• movement toolbar
• auto save/read camera calibration images (use 'r' to read previous image in current frame)
• calibration (camera,platform,lasers) and scanning (laser,angle) data saved to .ply file to use in future mesh processing
• some bugs fixed
• support for OpenCV 4.x

P.S. Project is work in progress so at some moments letest commits can be non functional or contain some debug console output.

Discussion board:
https://vk.com/topic-99790498_40015734

Night Gryphon
ngryph@gmail.com
http://vk.com/wingcatlab

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Calibration

!!! WARNING !!! Current machine defaults are set for my custom hardware. To use with Ciclop hardware you need to adjust 'settings.json'. At least: platform diameter=200, all offsets = 0, machine_model_path=ciclop_platform.stl Take a look at README_custom_machine.md

General calibration process is:

• if needed set machine custom parameters (turntable geometry, board init string, etc...) in 'settings.json' file. It is created automatically after first run with default values. Check README_custom_machine.md
• make sure you can turn on/off lasers and move platform in correct direction with toolbar buttons. Use "Control workbench"
• check camera resolution and set focus for autofocus cameras at "Calibration"->"Video settings"
• using "Calibration"->"Pattern settings" setup pattern cols/rows/dimensions
• using "Adjustment" workbench adjust camera exposure/brightness/contrast to clearly capture pattern and lasers
• using "Adjustment" workbench adjust segmentation parameters to detect laser lines with minimum noise
• using "Calibration"->"Camera intrinsics" calibrate your camera focal length and distortion
• using "Calibration"->"Laser triangulation" detect the laser planes position
• using "Calibration"->"Platform extrinsics" calibrate platform position
• check calibration quality by calibration visualization for pattern/platform/laser lines positions

Notes

1. Do not oversharp/overtight images in laser capture adjustments. A bit blurry laser line before segmentation filters provide subpixel position information. Oversharped image create wobbly "pixel stairs" style artifacts at the 3D scan.

2. Using ROI increase overall scan precision by removing noisy surroundings from laser point detection input

3. If you wish to use segmentation equival to Horus 0.1 than set: YCrCb filter, blur and window filters off, refinement off

Camera calibration

To get better scanning results you has to calibrate your camera using "Calibration"->"Camera intrinsics".
Gryphon Scan use multistep camera calibration to get better precision. Each next camera calibration use previous results as starting point.

Steps to calibrate camera:

1. Measure rough initial camera intrinsics. For Logitech C270 you can use the default initial values and skip to next step.
   If your camera is not Logitech C270 it is better to estimate rough focal length using ruler and some linear target. As calibration target you can use another ruler or just something straight.

• Measure your target length and fill in "Targrt length" field
• Put target horosontally and parallel to camera. Move target back/front so it exactly fit in to camera frame. Measure distance from camera to target and fill "Target horisontal dist" field
• Do the same for vertical target and fill "Target vertical dist" field
• Check the calculated camera matrix and if it look good than apply with "Apply calculated camera data" button.

2. Using your chessboard pattern calibrate precise camera matrix and distortion.
   The chessboard pattern has to be flat and rigid as possible. Capture 15 frames of calibration data moving pattern all around the camera view. Keep patten parallel to camera. To capture frame press [space]. Frames are only captured if pattern is detected within frame.

All captured frames are automatically saved to camera_intrisics folder. You can recall them one by one by press [r] button during frames capture.

Some reading

The Intrinsic Matrix:
http://ksimek.github.io/2013/08/13/intrinsic/

The distortion vector:
https://docs.opencv.org/3.1.0/dc/dbb/tutorial_py_calibration.html
https://www.cs.auckland.ac.nz/courses/compsci773s1c/lectures/camera%20distortion.pdf

Laser calibration

Using "Calibration"->"Laser triangulation" make two calibration sequences with different chessboard pattern positions.

• Put the pattern slightly in front of platform center. Run first calibration. You should see laser traces forming two planes during calibration.

• Put the pattern slightly below of platform center. Run second calibration choosing to continue previous calibration. You should see laser traces append to previous ones forming cross of planes.

This will make calibration more precise by using larger lasers point cloud area.

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Point clouds misalignment

Still investigating. As general workaround try to keep things symmetrical/parallel/perpendicular.

NOTE If cloud misalignment is very big than check your hardware and connections. Check is platform rotation direction correspond the buttons? May be your stepper cable turned upside down or you misconfigure rotation direction flag? Is there any not well fixed parts? Etc...

Lasers

For Gryphon Scan laser planes position and tilt does not affect on point cloud misalignment. During some tests i move lasers left-right, back-front, tilt, slightly change focus etc and this does not cause any noticible point clouds misalignment.
I plan to do more investigations later.

- laser to camera distance should be equival
- laser lines should be vertical
- laser lines should cross at platform center

Platform

Platform calibration is the most critical.

• to get better platform calibration put pattern in the middle of turntable.
• platform center should be in the middle of horizontal axis of camera image
• platform rotation axis should be vertical in camera image and parallel to image plane
• platform should be perpendicular to rotation axis

Here is how platform offset vector affect the clouds alignment:

Change X value

The X coordinate (horizontal) mostly affect clouds scaling artifacts

Change Y value

The Y coordinate (vertical) mostly affect general position of mesh on the vertical axis

Change Z value

The Z coordinate (depth) mostly affect clouds rotation artifacts

Model correction tool

You can manually adjust model after scan or load and correct existing .ply. Tool allow to apply platform center offset to manually compensate calibration error.
Also you can do a test scan and manually find offset to adjust platform calibration for further scans.
To adjust saved .ply it has to be saved with Gryphon Scan and contain scanning metadata.

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Capture performance

Video flush values

Most web cam drivers use buffer of few captured frames to enchance performance. But in case of scanning we need current frame not the buffered one. To flush the buffer and get the current frame the specified amount of frames are pre-read from camera driver. But this also slowdown the image capture because there is no way to surely detect which frame is actual not the buffered one.

You can adjust the number of flushed frames in 'settings.json' to optimize performance or to fix 'jump' artifacts in scan. The parameters are: flush_stream_* and flush_*
The flush_stream_ is values for user interface preview mode. The flush_ is for calibrating/scanning mode.
Values are:

    [ texture capture flush,
      laser capture flush,
      pattern capture flush,
      change mode flush ]  

• If the value is positive number it is treated as the number of frames to pre-read. Typically 3-4 is enough.
• If the value is negative it is treated as number of milliseconds for automatic flush mode. It will try to detect an actual frame by measuring frame grabbing time. If frame grab time is more than specified number of milliseconds than frame treated as actual frame. But this timings are depend on overall system performance etc so is not perfect. For logitech C270 typical actual frame grab time is 25-30ms so you can try -30 value. The number of auto flush frames is limited to 4 frames to prevent possible lockup.

Multithreading

During scanning Horus use two separate threads to capture data and to process data. If automatic flush is used the processing thread can affect frame grabbing time causing false positive detection of current frame which will cause slices "jumping" out of the model. To minimize this effects you can pause processing during capture frames. To enable set "scan_sync_threads": true in 'settings.json'

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Installation

At the moment there is no automatic installer so you need to install Python and requred libraries manually then download and run Gryphon Scan.
Yes, there is bundler scripts in Horus but there is a lot of broken download links and old software versions. Also i plan to switch to new OpenCV with contrib package (4.1.0 at the moment)

Windows: Installing Python 2.7 for Gryphon Scan

This notes can be incomplete. This is my experience for my environment (Win 8.1)

1. Get and install latest Python 2.7
   https://www.python.org/downloads/release/python-2716/
   Windows x86-64 MSI installer

2. Get and install Microsoft Visual C++ Compiler for Python 2.7
   Required to compile some lib's during pip install
   http://aka.ms/vcpython27
   http://www.microsoft.com/en-us/download/details.aspx?id=44266

3. Get and install wxWidgets 3.0.4.
   The 3.0.4 is required for matplotlib==1.4.0. Will switch to new versions later if required
   https://sourceforge.net/projects/wxpython/files/wxPython/3.0.2.0/
   wxPython3.0-win64-3.0.2.0-py27.exe

4. Install OpenCV-contrib

pip install opencv-contrib-python  

Note: do NOT install opencv-python. Only install opencv-contrib-python

5. Install OpenGL

pip install pyopengl pyopengl-accelerate

Also pip package require GLUT DLLs to be installed separately
http://freeglut.sourceforge.net/index.php#download
https://www.transmissionzero.co.uk/software/freeglut-devel/
Download "freeglut 3.0.0 MSVC Package"
Extract and copy \freeglut\bin\\[x64\\]freeglut.dll -> \Python27\Lib\site-packages\OpenGL\DLLS\freeglut[64].dll
For 64 bit python you need to rename DLL to freeglut64.dll

6. Install packages with PIP

pip install -U pyserial numpy scipy matplotlib==1.4.0

MacOS: Setting Python for Gryphon Scan

I'm new in Mac world so please correct me if i miss something.

1. Mac OS already have python 2.7 installed

2. Install package managers and stuff

sudo easy_install pip
sudo pip install tornado   <- this will ask to install developers tools which is ok
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

3. Install wxPython 3.0 (Yes, the 3.0.x version required) Download package from
   https://wxpython.org/snapshots/
   Unpack and install with (you can install with command line or turn off Gatekeeper as package have no digital signature)

sudo installer -pkg /path/to/wxPython.pkg -target /

4. Install packages

sudo easy_install -U numpy <- i've got a huge bunch of warnings and few errors during compile but it seems OK in the final
sudo pip install opencv-contrib-python
sudo pip install pyopengl pyopengl-accelerate
sudo pip install -U pyserial scipy 

5. Setup matplotlib 1.4.0

brew install freetype
easy_install -U matplotlib==1.4.0

6. Download Gryphon Scan

git clone https://github.com/nightgryphon/gryphon-scan.git

7. Build USB camera controls library

cd gryphon-scan\src\horus\engine\driver\uvc\mac
make

8. Run the app

gryphon-scan\horus

You may need to allow this app to run in settings->security because there is no digital signature

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For the original Horus README look at README_Horus.md