HOT SPOT DETERMINATION

HOT SPOTS POSE SERIOUS PROBLEMS IN THE PHOTOGRAPHY OF FORESTED AREAS, WHERE COLOR FILMS ARE USED AND HIGH SUN ANGLES ARE ENCOUNTERED. A HOT SPOT, WHEN APPLIED TO AERIAL PHOTOGRAPHY, IS A BRIGHT REFLECTION 180 DEGREES AWAY FROM THE DIRECTION OF THE SUN. AERIAL PHOTOGRAPHERS OPERATING IN THE SOUTHERN TIER OF THE STATES IN THIS COUNTRY, AND IN THE TROPICS, NEED TO BE AWARE OF THE HOT SPOT PROBLEM AND ITS SOLUTION. IT IS IMPORTANT TO AVOID THIS EXPOSURE ANOMALY IF HIGH QUALITY PRODUCTS ARE DESIRED FOR ANALYSIS BY PHOTOMETRY AND DENSITOMETRY. THE HOT SPOT PHENOMENON HAS RECEIVED VERY LITTLE ATTENTION BY AERIAL PHOTOGRAPHERS LARGELY BECAUSE IT IS MOST TROUBLESOME OVER FORESTED AREA IN LATITUDES WHERE THE SUN ANGLE IS HIGH, SUCH AS IN THE HOUSTON AREA. A SUN ALTITUDE NOMOGRAM MAY BE USED TO GRAPHICALLY COMPUTE THE HOT-SPOT-FREE TIME. THE PAPER PRESENTS AS AN EXAMPLE A SOLUTION FOR 30 DEGREE LATITUDE AREAS, BUT SIMILAR SOLUTIONS CAN BE EASILY WORKED OUT FOR OTHER LATITUDES. A TABLE AND GRAPHS OF HOT-SPOT-FREE TIMES ARE PRESENTED AND THESE CAN BE USED TO PLAN PHOTOGRAPHIC MISSIONS. SMALL AMOUNTS OF HOT SPOTTING CAN OCCASIONALLY BE TOLERATED FOR MOSAIC PURPOSES, AND DIRECTIONS ARE GIVEN FOR COMPUTING PERMISSIBLE AMOUNTS. HOT SPOT AND SUN REFLECTIONS ALSO AFFECT THE DATA FROM ELECTRO-OPTICAL SCANNERS, BUT THIS IS BEYOND THE SCOPE OF THIS PAPER. /AUTHOR/

  • Authors:
    • Heath, G R
  • Publication Date: 1973-11

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Filing Info

  • Accession Number: 00203052
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 27 1974 12:00AM