Palette selection for animal surveillance

People have been asking about using thermal cameras to do surveillance of animals up trees during logging operations as a way to make sure that they aren’t doing any damage to the wildlife in these areas. It sounds like a great idea, and thermal imagery definitely has a good place in spotting wildlife, but incorrect ranging and palette selection can be detrimental to proper identification.

Here are a series of images of the same possum, with different palette selections.

Image 1 is a simple rainbow palette with auto-scaling:

Image 2 is slightly reduced scaling in Greyscale HC (black and white with red as a high wash colour):

Image 3 is drastically narrowed Greyscale HC

Image 4 is a wide Greyscale (not HC) with green used as an isotherm colour for anything between 21 and 34°C

As you can see, palette selection gives you quite different results. I would be most happy with either image 2 or image 4, but if I needed to do quick scan and investigate jobs I would move towards a scale like that in image 3.

The images also show the difficulty of good identification of animals at a distance. The only spots on the animals that are significantly different in temperature to the environment around them are their eyes, nose and limb extremities. These would be quite small targets to try to spot at 40-50m away, up a tree canopy obscured by leaves, so I would recommend making sure that your equipment is up to the task before attempting to use thermal imaging as part of a wildlife protection program.