I am analyzing a Landsat 5 TM image, and the Band 3 (red) appears almost completely black, with very little to no visible details. What could be the possible reasons for this issue? Could it be related to atmospheric conditions, sensor calibration, or data processing errors? I would appreciate any insights or suggestions on how to resolve this.
• Check Pixel Values: Use the Identify Tool in
ArcGIS to inspect pixel values.
• Apply Contrast Stretching: Use Min-Max or
Histogram Equalization.
• Re-download the Data: If corruption is
suspected, get a fresh copy from the source.
I hope this will help.
@Kunanayagam Thanuraj
The most likely reason for the dark appearance is the presence of clouds. Since you're using QGIS, you can visually enhance the image using the image enhancement tools available in the Raster toolbar. The toolbar provides various display options to adjust and improve how the image is rendered.
Quick troubleshooting:
1. Did you visualize the image in the correct way, stretching the range of values? Since I see some bright details, I guess the answer is yes.
2. What kind of surfaces are we looking at? Green vegetation reflects NIR (Landsat 5 band 3) but water absorbs it, etc. Check which landcover you expect in the area. It looks like an island or a peninsula with some agricultural parcels, is that correct?
3. Can seasonality have an impact? I see that your image was recorded on April 14. If it is from the Northern Hemisphere, it could be that the vegetation is not yet green everywhere. So you'll see the grasslands reflect NIR, but the croplands not yet, because the crop has not germinated yet. For deciduous trees and shrubs it can also be too early in the growing season.
- Badges
- Science topic
- Similar topics
- Computer Communications (Networks)
- Simulators