Influence of incident angle and laser footprint on precision and level of detail in terrestrial laser scanner measurements

Mahmood, Sajid (author), Majid, Zulkepli bin (author), Idris, Khairulnizam bin M. (author), Hamid Chaudhry, Muhammad (author)

Terrestrial laser scanners (TLS) are used for a variety of applications, e.g., surveying, forestry, cultural heritage preservation, mining, topographic mapping, urban planning, forensics etc. This technology has made a huge shift in 3D spatial data collection due to much faster speed compared to other techniques. In the absence of guiding principles for positioning TLS relative to an object, surveyors collect data at maximum arrangements of scanning geometry elements due to fear of incomplete data of TLS. In 3D spatial data acquisition, positional accuracy and Level of Detail (LOD) are major considerations and are dependent on laser incident angle, footprint size, range and resolution. Mathematical models have been developed relating range, incident angle and laser footprint size for different surface configurations. These models can be used to position TLS to collect data at required positional accuracy and LOD. Models have been verified by deriving one model from other surface models by changing parameters. Effects of incident angle and footprint size have been studied mathematically and experimentally on a natural sloping surface. From the results, surveyors can plan the positioning of the scanner so that data is collected at the required accuracy and LOD.

• Language: English
• Keywords: Terrestrial laser scanning, Incident Angle, 3D surveying, Digital Terrain Model, Point cloud
• Work type: Scientific work
• Typology: 1.01 - Original Scientific Article
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Publication status: Published
• Publication version: Version of Record
• Article acceptance date: 09.10.2020
• Publication date: 05.06.2021
• Year: 2021
• Number of pages: Str. 260-281
• Numbering: Letn. 65, št. 2
• PID: 20.500.12556/RUL-132764
• UDC: 528.71
• ISSN on article: 0351-0271
• DOI: 10.15292/geodetski-vestnik.2022.01.260-281
• COBISS.SI-ID: 70113795
• Publication date in RUL: 02.11.2021

Record is a part of a journal

• Title: Geodetski vestnik. glasilo Zveze geodetov Slovenije
• Shortened title: Geod. vestn.
• Publisher: Zveza geodetov Slovenije
• ISSN: 0351-0271
• COBISS.SI-ID: 5091842

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
• Licensing start date: 05.06.2021

Secondary language

• Language: Slovenian
• Title: Vpliv vpadnega kota in laserskega odtisa na natančnost in stopnjo podrobnosti pri terestričnem laserskem skeniranju

Abstract

Terestrični laserski skenerji (angl. terrestrial laser scanners % TLS) se uporabljajo na različnih področjih, kot so geodezija, gozdarstvo, ohranjanje kulturne dediščine, rudarstvo, topografija, urbanistično planiranje, forenzika ipd. Navedena tehnologija je močno spremenila zbiranje prostorskih podatkov v 3D, predvsem z vidika hitrega zajema podatkov. Ni veliko priporočil glede georeferenciranja oblakov točk, zato se v praksi poskuša zajeti kar se da veliko elementov geometrije skeniranih objektov, predvsem zaradi bojazni, da bodo podatki skeniranja nepopolni. Pri načrtovanju skeniranja sta med drugim izrednega pomena zagotavljanje položajne točnosti in stopnje podrobnosti (angl. level of detail % LOD), ki sta odvisni od vpadnega kota, velikosti laserskega odtisa, prostorskega obsega in ločljivosti. V raziskavi smo razvili matematični model za različne konfiguracije površja skeniranja ob upoštevanju prostorskega obsega, vpadnega kota in odtisa laserskega žarka. Razviti model pomaga pri izbiri stojišča TLS za zajem podatkov z zahtevano položajno točnostjo in stopnjo podrobnosti. Modele smo verificirali z izpeljavo enega modela iz drugega s spreminjanjem vrednosti obravnavanih parametrov. Vplive vpadnega kota in velikosti odtisa laserskega žarka smo obravnavali matematično in eksperimentalno za primer naravne poševne površine. Na podlagi predstavljenih rezultatov lahko načrtujemo ustrezen položaj stojišča TLS, s katerim bomo dosegli zahtevano točnost in stopnjo podrobnosti.

• Keywords: terestrično lasersko skeniranje, vpadni kot, 3D izmera, digitalni model terena, oblak točk