Fig. 3. (A) Thermogram of an Ord's kangaroo rat Dipodomys ordii taken in a laboratory enclosure set at 15°C, scaled to represent an 80° field of view with the animal 25 cm distant. (B–D) The results of convoluting that image with circular spread functions with the indicated half-angles _i). (E) The same animal imaged at 30°C. Both A and E use the same color representation of temperature and are marked with the full range of temperatures visible in each. (F–H) The results of convoluting that image. The color steps in B–D and F–H indicate temperature contrasts of 0.001°C. While spatial resolution is good at 15°C for the hypothetical _i=5°(D), contrast is only 0.003°C and the kangaroo rat is essentially invisible at 30°C (H). Temperature contrast is somewhat greater for _i=10° and 20°, 0.006°C in the 15°C cabinet, and 0.002–0.003°C in the 30°C cabinet.