Image ruler and its applications in distance and area measurement

Ti Ho Wang*, Ming Chih Lu, Chen Chien Hsu, Yin Yu Lu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


The paper presents a practical measuring system based a CCD camera and two laser projectors Because of the disposition of the laser projectors which are formed in parallel, distance between the projected spots always remains the same. However, the size of the laser-projected spots appearing in CCD image frames will vary according to the photographing distances. Analogue to a physical ruler, the proposed measuring method is therefore named as an image ruler because of its capacity in measuring distance and area via an established relationship between pixel counts and photographing distance. To overcome the problem of laser diffusion of projected spots generally occurred in existing measuring method, center of the projected spots can be accurately identified by a proposed method taking account of video signals of multiple scan lines. As a result, concerns about the diffusion effect of laser rays are also addressed and measurement accuracy is therefore not affected by this adverse effect. Simulation results have demonstrated that satisfactory results can be obtained via the proposed approach.

Original languageEnglish
Pages (from-to)901-907
Number of pages7
JournalWSEAS Transactions on Systems
Issue number5
Publication statusPublished - 2007 May
Externally publishedYes


  • Area measurement
  • CCD camera
  • Distance measurement
  • IBDMS (Image-Based Distance Measuring System)
  • Laser diffusion
  • Laser projector

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Computer Science Applications


Dive into the research topics of 'Image ruler and its applications in distance and area measurement'. Together they form a unique fingerprint.

Cite this