Interpreting Arial Photos

How would having this skill be useful?

5 areas to understand when evaluating photos Look for a scale Look for patterns, shapes, and textures Define the colors (including shadows) Find north Consider your prior knowledge

Look for scale Identify places you know This will help you think about how big something is Identify the scale of the map Is scale is not indicated look for something you know the size of to compare

Look for patterns, shapes and textures Straight lines are the result of human land use Roads, farm fields, buildings, ponds Bodies of water are easy to identify Lakes, stream and ocean have unique shapes Clear cut forests are cut in squares Planted trees look like they are in straight lines Different shades of green identify stands of timer that are different ages

Patterns and Textures Cont. Mountain Ranges appear to be long, sometimes wavy lines Cliffs are squiggly or dark lines framed by a shadow Mountains look like wrinkles or bumps.

Relief Inversion Sometimes the lighting make mountains look like valleys Our eye expects the sun to come from the upper left corner. When the sun is coming from other angles it can be confusing. You can turn the picture so the light come from the upper left corner.

Define Colors Water can be many colors Clean water absorbs the light and looks black or dark blue Water with dense sediment looks brown After rain or an event that can “stir” the pond up As the water settles it can look green then blue The sunlight can reflect and look grey, silver or white Frozen water can look white, gray or slightly blue

Plant colors Grassland – pale green Forests - dark green Agriculture – bright green Seasons can change the colors

Other Colors Bare or very lightly vegetated ground is usually some shade of brown or tan Residential areas, cities, and other densely built areas are typically silver or gray

Find North As long as you know where north is you can figure out lots of things Directions of roads, rivers, mountians

Consider your Prior Knowledge Think about the places that you know and how they look on satellite images Use that information as you look at other images