GIS5027 Module 1: Visual Interpretation

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In a blink of an eye, I have returned with new maps for my second GIS grad course!

Not much of a break in-between the first course and this next one, but hopefully with the closing of the last class, I can continue the momentum into the next, which is Remote Sensing and Photo Interpretation.

Module 1 covered Visual Interpretation based on 3 different parts: identifying tone and texture, identifying features, and interpreting color.

For part one, we had to identify tones from light to dark and textures by how fine to coarse areas were in this USGS historical aerial from 1965. We did this by creating two separate feature classes for tone and texture, giving them both a new text field in order to name each feature record accordingly. Manually, we digitized areas they showed these variations in tones and textures. After doing so, we simply had to create a map layout, which is becoming one of my favorite parts of the map making process. The creativity aspect of it all really scratches that part of my brain.

I think the hardest part was identifying the "Very Light" tone, especially since I didn't want to copy the examples provided -- I wanted to really practice and the very light areas (that weren't mottled in my eyes) were quite small or minimal to begin with. However, at the end of it, I was happy to get back into map making and was content with the layout created here shown below.

Screenshot of the Visual Interpretation Lab Part 1: Identifying Tones & Textures Map. The magenta polygons represents toned areas, while the yellow polygons represents textured areas in the USGS 1965 historical aerial provided from UWF GeoData Center.

In part two of the lab, focusing on identifying features, [in-progress, to be updated upon completion]... We identified features based on 4 different factors: shape/size, shadows, patterns, and associations. It was interesting to have to think of features in this way when scanning through the USGS historical aerial from the 1970s. Having worked with historical satellite imagery, it's cool to see the technical side of imagery analysis -- having been working on autopilot and not really knowing the technicalities and conceptual reasoning behind why things are perceived in these kind of aerials is fascinating and cool.
Screenshot of the Visual Interpretation Lab Part 2: Identifying Features. The red points represent features identified based on shape/size. The blue points represent features identified from shadows. The yellow points represent features identified based on patterns. And the white with black dot points represent association based features.

For part three, a map layout wasn't a requirement, but we were able to interpret colors in a True Color raster compared to its False Color version. It was so interesting to see the difference. I've worked with clients at work needing us to prepare offline Field Maps with historical aerials, recent true-color aerials, and infrared aerials for inspections throughout Florida. Truthfully, I was never actually analyzing them, so to be able to actually examine historical aerials and color aerials this closely was very eye-opening to me!

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