DTM's from stereo pair air photos

[BARNES DAVID]

Dear Grass Users,
        We would like to create DTM's or DEM's (is there any difference?)
from stereo pair air photos. Actually we are using very low altitude
(<70m) blimp photos and would like to see what our resolution is. Please
excuse this elementary question from an uninformed Geologist!
Thanks in advance,
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  * DAVE BARNES                                                            *
  * Geology Dept.                                                          *
  * Western Michigan University                                            *
  * Kalamazoo, MI 49008                                                    *
  * FAX# 616-387-5513, phone 616-387-5493                               
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  * barnesd at lab.cc.wmich.edu                                               *
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