Science Buddies: "Ask an Expert"

how a camera can be used to measure heights and distances ?

Hi,

I think there are many answers to your question. Here is one that ,easures distance by the change of light intensity:

https://www.sciencebuddies.org/science- ... p034.shtml

Here is a distance measurement by using parallax:

https://www.sciencebuddies.org/science- ... p019.shtml

You can measure height by comparing the unknown height object to a known height object next to it. Distances can be measured the same way if the objects are horizontal.

People also often take two pictures of the same scene from two positions a known distance apart, and deduce distance from parallax measurements. Astronomers often carefully study shadows cast by moon or planent crater walls to measure how deep the craters are if they can tell the angle of illumination. The same idea can be used to construct three dimensional models of faces or other objects from two dimensional photographs by studying the lighting of the photo and shadows cast by the features in the photo.

One can also use the distance of the camera lens to the focal plane (where the film or sensor is) and knowledge of the lens shape to determine the distance from the lens to the object being photographed when the target object is perfectly focused on the focal plane to determine the distance from lens to object.

You may want to look at this website on Photogrammetry (the interpretation of photographs) for more information:

http://rst.gsfc.nasa.gov/Sect10/Sect10_3.html

http://www.optical-metrology-centre.com ... mmetry.pdf


This whole website on Remote Sensing may also be of interest:

http://rst.gsfc.nasa.gov/

http://www.grss-ieee.org/education/tutorials/

If you really want to delve into this subject deeply, look at this site:

http://www.ins.itu.edu.tr/foto/hdemirel/new_page_32.htm

I hope this answers your question.

Best regards,

Barrett L Tomlinson