1. 3D Room Surface Mapping Neil Brazeau, Franck Dzefi, Jackline Koech, Nicholas Mosher Faculty Advisor: Prof. Mario Parente Department of Electrical and Computer Engineering ECE 415/ECE 416 – SENIOR DESIGN PROJECT 2012 College of Engineering - University of Massachusetts Amherst SDP 12 Overview: The 3-D room surface mapping project is designed to scan a room using a Ryobi® laser distance meter, obtain coordinate data and reconstruct the data using Meshlab and a C program to obtain a 3-D model of the main features of a room. With the distance measurement device and synchronized motion control, we would be able to record accurate distance measurements between the device and a specific point on the surface of a room. Using Stepper Motors which provide accurate movement, we can develop a stable mechanism to control the orientation of the laser measurement device. With the help of a programmed microcontroller we can send our data points to a personal computer. Using Meshlab, a free program that offers numerous 3-D rendering filters, we can process the data obtained from the microcontroller and construct a 3D representation of the room. Electronic Hardware: Ryobi Tek4 Laser Distance Meter: Common internals to many meters on the market Test and communications pads produced no control Porcupine Electronics LR3 interface board Imitates the meter’s keypad, screen, and power supply, giving full serial and USB control 10 measurements per second constant read rate Accurate to within 1.5mm per 30 meters Arduino and the Adafruit Motor Shield: Open source and personally owned Easy control of both stepper motors with I/O pins and power to spare Easy serial communication with the LR3 interface board and the PC Mechanics: SYSTEM CHASSIS: - CAD assisted design to minimize materials and size. - Lightweight aluminum. - Precision milled to a tolerance of +/- 0.0005 inches. - 155º Inclination / 360° Azimuthal Sweeping of Sensor - Adjustable feet for leveling with visual 2-axis bubble. - Easy disassembly/reassembly with standard slot/hex fasteners. - Mounting provisions for slip-ring wiring system. STEPPER MOTORS: - Dual Portescap 42M Series Bi-Polar Geared Motors - 5V Operating Voltage - Unidirectional 0.15° Step Accuracy (1.5º Bidirectional) - 11.9 / 84 (oz-in / mNm) Holding Torque Software Communication: With the Help of Visual C# we created a small user interface to handle the serial communication from the Arduino chip to PC. The software does the following: READ SERIAL DATA Read serial data from Arduino chip Display the serial data in our GUI Save the data in.csv or.txt file CONVERT SERIAL DATA Convert serial data from spherical coordinates to Cartesian coordinates Output a final.csv file for 3-D rendering Results: Accuracy of the laser far is beyond our requirements, though at higher measurement rates results are less accurate and inconsistent. Precision determined by motors and gearboxes. 1.5 degrees of gear lash per box, but scanning process decreases the effects. Our Resolution goal of 6 inches at 50 feet would require 1.5 degrees of resolution. Our minimum of three degrees only allows for 6 inches at 9.6 feet, 81% less effective range than hoped. Our Scan Time goal of 15 minutes for full spherical scan was not met. With an average of 8 seconds per high-precision measurement and a 3-degree resolution, it takes 16 hours for a complete scan of a room. A lower-precision scan takes anywhere from 20 minutes to 4 hours. Special Thanks To: LR3 Laser USB/Serial Interface Board Porcupine Electronics, LLC porcupineelectronics.com Budget: Billed: Stepper Motors (2): $55 each Ryobi Laser Meter: $99 LR3 Interface Board: $149 Replacement Electronics: $70 Total Billed (Of $500): $428 Donated: Aluminum and Plastic Stock: $100 Mechanical Accessories: $25 Arduino UNO: $20 Arduino Motor Shield: $20 Total Billed + Donated: $593 Precision CNC Manufacturing David Farnum Lathe Operation and Mechanical Advice MeshLab Open Source Mesh Processing Software Visual Computing Lab - ISTI - CNR http://meshlab.sourceforge.net/ 3-D Rendering: We use Meshlab to construct a 3-D representation of the surface. Meshlab: Open source software Offers a good three dimensional visual environment. Can handle large unstructured point clouds Features: Filtering, data editing, hole-filling and noise removal using smoothing filters. Point Cloud surface reconstruction algorithms: Marching Cubes Ball Pivoting. Poisson’s Surface Reconstruction Reconstruction obtained with simulated data Nick attaches a motor Franck mimics a wall for a test scan

2. Our test “room” A quick scan’s result A slow scan’s result Neil fixes the Arduino codeJackline renders data in Meshlab