Scenes with wide temperature ranges won't show the gradient because the gradient only shows itself when the palette is squished to fill a small range.
Nope, you call gradient something that in fact is thermal image destruction in the corners and is more visible in one of them for reasons I wrote and modeled with glass block.
Wide temperatures are even on this router thermal image and image destruction easy to see in the corners even from raw sensor data calibration frames provided there earlier-a few averaging makes this cleary visible and after this small mechanical investigation I've made now fits into this what is seen there in one of these flat surface frames.
We'll se how it will look like on latest raw sensor data provided by @miguelvp - those output images by @miguelvp are not compenated and horizontal lines still visible-more advanced image processing is neded there.
In this @Mike photo from its Seak teardown there is no such small range but temperature difference close to 5*C on flat surface and it is not acceptable for anything more serious but the toy.
Another review - now we know where to look for image destruction and catch this worst case scenario corner where most of the heat comes inside sensor cage
Probably there below i sno reason for such warm corners while it is pointed on the table-my guess is gradients in the corners visible and there is nothing to compare to higher price Flir equipment-from its mechanical design now we know Seek Thermal dongle for the moment is a thermal toy
Thx, @mikeselectricstuff for this thread and teardowns - I've saved $200
Update:
Another example in dark night... complete destruction of thermal image at the corners with one much stronger than rest of the other corners,
but ok depending on wind conditions and ambient temperature there maybe air heated by this animal created this aurora and it is not close to animal shape, but you never know while this deveice is not reliable...
OK, lets wait for hardware update of Seek Thermal and than maybe will give them the second chance?