The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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Analysis of the Existing Visual Performance Based Mesopic Models and a Proposal for a Model for the Basis of Mesopic Photometry

Meri Viikari

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Electrical and Communications Engineering for public examination and debate in Auditorium S1 at Helsinki University of Technology (Espoo, Finland) on the 14th of December, 2007, at 12 o'clock noon.

Overview in PDF format (ISBN 978-951-22-9122-9)   [592 KB]
Dissertation is also available in print (ISBN 978-951-22-9121-2)

Abstract

The work started with outlining the current status of photometry. The origins of the photopic spectral luminous efficiency function V(λ) were extensively investigated. The work continued to examine the ability of the existing photopic spectral luminous efficiency functions V(λ), VM(λ), or V10(λ) to describe peripheral photopic vision. The conducted reaction time measurements indicated that none of the existing functions described the peripheral vision correctly. A new photopic spectral luminous efficiency function for peripheral vision Vper(λ) is proposed for the photopic end with which the mesopic photometric model should merge at the upper luminance limit of the mesopic region.

The work continued to review the existing mesopic photometric systems. The previously proposed mesopic models are mainly based on brightness matching, which does not preserve additivity. The two recently proposed mesopic models, MOVE-model by the MOVE consortium (Eloholma 2005) and the X-model by Rea et al (2004), are based on visual task performance. Performance based mesopic models are claimed to preserve additivity within the given light level. The two performance based models are currently being analyzed by the CIE TC 1-58 in order to result in an internationally agreed system for performance based mesopic photometry.

The work continued to generate contrast threshold and reaction time data in order to compare the existing performance based mesopic models. The differences between the mesopic luminances predicted by the two models are evident. Also the upper transition points of the models between the mesopic and photopic regions are very different.

Finally, the work concluded by proposing a new performance based mesopic model. The new model is based on the same experimental data as the MOVE-model. Thus the newly proposed model is assigned as a modified MOVE-model. The modified MOVE-model was compared along with the other two performance based models using three independent experimental visual performance data sets. The comparison indicated that the modified MOVE-model described the experimental data best.

This thesis consists of an overview and of the following 5 publications:

  1. Viikari M, Eloholma M, Halonen L. 2005. 80 years of V(λ) use: a review. Light & Engineering, 13 (4): 24-36. © 2005 Znack Publishing House. By permission.
  2. Orreveteläinen P, Viikari M, Halonen L. 2005. Make way for peripheral V(λ). Light & Engineering, 13 (3): 23-34. © 2005 Znack Publishing House. By permission.
  3. Eloholma M, Viikari M, Halonen L, Walkey H, Goodman T, Alferdinck J, Freiding A, Bodrogi P, Várady G. 2005. Mesopic models—from brightness matching to visual performance in night-time driving: a review. Lighting Research and Technology, 37 (2): 155-175. © 2005 SAGE Publications. By permission.
  4. Viikari M, Chen W, Eloholma M, Halonen L, Chen D. 2006. Comparative study of two visual performance based mesopic models based on reaction time and contrast threshold data. Light & Engineering, 14 (4): 21-32. © 2006 Znack Publishing House. By permission.
  5. Viikari M, Ekrias A, Eloholma M, Halonen L. 2008. Modeling spectral sensitivity at low light levels based on mesopic visual performance. Clinical Ophthalmology, 2 (1): 1-13. © 2008 DOVE Medical Press. By permission.

Keywords: photometry, visual performance, mesopic model, spectral sensitivity

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© 2007 Helsinki University of Technology

Last update 2011-05-26