C o m p a r i s o n o f H a n d h e l d 3 D S c a n n e r s a t t h e D i s c h i n g e n C h u r c h S c a n P r o j e c t Dr.

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1 Comparison of Handheld 3D Scanners at the Dischingen Church Scan Project Dr. Philipp Raith 1

2 D i s c h i n g e n C h u r c h S c a n P r o j e c t Large scan project performed by FARO (R&D) of the church in Dischingen in July Goals of scan project: Flagship scan project for FARO Laserscanner S350 Test of features in development Market overview of handheld 3D scanners 2

3 S c o p e Field tests of our hand-held products in comparison to other sensors (mostly lowcost). Used Sensors: FARO Laser Line ProbeHD FARO Freestyle Objects Orbbec Astra/Astra S DotProduct (DPI7) Intel SR300 ASUS Xtion Artec Spider Google Tango 3

4 Test method Scanned objects: main altar (all sensors) statue close to altar (all sensors) statue outdoor (some sensors) church bell (some sensors) Same scanning conditions for all sensors. We tried to evaluate as fairly/objectively as possible. The results refer only to the measurements of the tested units in this specific scan project. Scanning of other objects or under other conditions may lead to other results. 4

5 Faro Laser Line ProbeHD Very high accuracy 0.07mm Very detailed model Gaps: No color Long scanning time (~45 min for the statue) 5

6 Freestyle Objects Smooth color Very detailed Large scanning volume High sequence precision ~1mm High sequence accuracy ~1.5mm Gaps Unnatural color (statue: yellow) Good sequence accuracy (1 but only after postprocessing with loop-closing 6

7 Orbbec Astra Short capture times Low weight High point density Gaps: Color quality (mapping artefacts) Rather low resolution Quite high noise and low accuracy (~5 mm) Short range (about 1,2m) Largely interpolated data High probability for motion blur in dark environments leads to lost features, lost tracking and perhaps also layering artifacts Sensitive to sunlight 7

8 Google Tango Extremely robust, fast and intuitive live tracking Runs on a small tablet Range about 3m Relatively low error drift Occlusion-based filtering of erroneous geometry Gaps: very low resolution Accuracy only around a few cm washed-out look, no crispness, everything blends together 8

9 DPI 7 Very good color quality High point density Comparably stable tracking Gaps: Color mapping artifacts Resolution ~10 1m Accuracy ~5 1m Interpolated 3D data Limited absolute length of one scan. For larger projects, registration is thus necessary as a post-processing step. 9

10 SR300 (Intel RealSense TM ) The sensor is tiny, light and cheap. Dense recording of flat/slightly curved surfaces The colors appear to be fairly close to reality. Gaps: The tracking was poor. We did not succeed to record larger non-trivial objects. Accuracy is low. Precision is low. Lots of tilted geometry and detached geometry/noise. Layering artifacts. 10

11 Artec Spider High accuracy up to 0.05mm (according to data sheet) Resolution: up to 0.1mm 7.5 fps live tracking Gaps: We were not able to capture large enough parts of the statue or the altar to allow a comparison with other sensors Close range: m High risk for layering artifacts Many cases of lost tracking 11

12 Asus Xtion Fast recording times allow for a good workflow. The tracking performance appeared equal or better to Freestyle when scanning from a distance of 1-2 meters, but worse for closer distances The sensor is tiny and light. Recorded surfaces appear dense. Gaps: Handling the scanner while moving was difficult. The colors look artificial, almost computer game like. Lots of layering artifacts. The colors of the same surface can suddenly appear differently during the same scan. Areas covered by direct sunlight were not recorded. Large amounts of RAM required for processing (>100 GB). Rather low accuracy. 12

13 Overview FARO Laser Line ProbeHD FARO Cobalt Array Imager Sensor Astra Astra S Google Tango SR300 Xtion DPI7 FARO Freestyle O Color Quality NA ++ Noise Resolution Accuracy Tracking NA - Processing Time RAM Sunlight Performance Capture Time approx. Price ( ) K 12K 40K 18K ++: very good --: poor 13

14 Conclusions The tested scanners differed a lot with respect to resolution, accuracy, noise and color quality. 14