Thursday, February 9, 2017

Remote Sensing - Intro to ERDAS Imagine

Lab Objectives:
  • Calculate wavelength, frequency, and energy of EMR
  • Locate and use basic tools in ERDAS Imagine
  • Learn about and use the Viewer to view data in ERDAS Imagine
  • Subset data in ERDAS Imagine as a preprocessing step for making a map in ArcGIS

ERDAS is a computer program specialized for remote sensing data. This program is new to me, but the lab this week was a good introduction to ERDAS. The lab began with the first exercise, giving a quality introduction to important remote sensing concepts, such as EMR, wavelength, frequency, light spectrum, etc.

The second exercise really focused on the ERDAS program. I was introduced to important introductory information, such as the overall layout/interface of the program, adding data to different specifications, navigating controls like zoom and pan, and using multiple viewing windows to work with more than one image at a time. Towards the end of exercise 2, the exercise showed different types of imaging techniques and combinations of bands, such as False Natural Color and False Color IR. Different bands can reveal or "highlight" certain objects and/or land cover.

The third and last exercise revolved around data preparation with ERDAS and map-making with that data. A remotely-sensed raster image was used, and it showed classified land areas, such as bare ground, cloud, water, riparian, and vegetation classed by aspect. Each class was made up of a combination of red, green, and blue bands. Using this preliminary image, a subset image was taken of a small area using ERDAS. This subset image was added to a viewing window in ERDAS, and an area column was added to the attribute table of the subset image. Area (in hectares) was calculated for each classification type. After editing this attribute table, the image file needed to be saved again.
This saved image was then added to ArcMap, and the classes were reclassified. A map was then created to display the classes in the study area.

Overall, this lab was a little time consuming because I was learning a new GIS program. However, it was enjoyable to apply remote sensing techniques/images to GIS and see "real world" applications.




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