spectral profiles

Questions:

1. Display and compare differences of the spectral profiles between the ELC image and the original image for (Hint: You need to display, describe the differences, copy/paste spectral profiles of ELC image and original image):

– Healthy Vegetation (sample 2290, line 620)

– Urban (sample 110, line 151)

– Sea Water (sample 1246, line 455)

2. Do you think the ELC method corrected the atmospheric effect very well? What errors might be included in your ELC method (Hint: Spatial and temporal errors, not perfectly matching between image spectra and in situ/field spectra; white point(s) is not whitest and black point(s) is not blackest, leading to negative or >1 ELC pixel values)? Evaluate your ELC result (Hint: Check ELC image profiles patterns and percentages of negative and > 1 ELC pixels).

3. Which features (targets, land cover types) have a possible negative reflectance or the reflectance larger than 1 per band (Hint: you might want to use Display/Profiles)? Why do you think your result has the reflectance less than 0 or larger than 1 (Hint, Not so whitest and blackest for image spectra for simulating calibration models)? How can you fix the problem (Hint: Either re-do ELC or assign all unreasonable ELC pixel values within 0 – 1)?