Lab 2 - Visual Interpretation

GIS 4035

 

 

 

In this weeks lab and lecture we learned about identifying tone and texture in an aerial photograph.  Above you will see areas that are defined by their tone.  Tones are defined by the brightness or darkness an area displays on an aerial image.  This varies from a very light tone, all the way up to the very dark tones.  Also in the above aerial, I show different textures.  Texture is how rough or smooth a surface looks when viewing the aerial photo.  I have shown a range from very fine texture (water) all the way up to a very rough course texture (housing development).

 

 

 

 

The map above identifies features based on shape/size, shadows, patterns, or associations.  Shape and Size of features is a common way that analysts look at aerial photos and quickly determine what they are looking at.  Roadways, Buildings, Water bodies can all be identified in the photo by the way they look and the size they are relative to their surroundings.  Shadows help show the viewer what may not be clear with an initial viewing of the photograph.  Take for instance the water tower, sign and Utility Pole, all of which can easily be identified on the ground but from the air, may be more difficult.  Shadows help the analyst make a better determination of what is on the ground.  Pattern is also used by analysts to determine what they may be looking at.  Housing developments, Vegetation, and Parking Lots can be looked at and by a pattern show the user what they are looking at.  Finally, through association we can make a determination of what we are looking at.  The end of a major water body and the pier makes it easy to associate a beach to the coastline.  While a pool and building shape, with cars and a parking lot helps the analyst determine a hotel is present.