Recognition of inner structures.

(A–D) Comparison of spatial resolution at different tracking arena sizes. The image shows the output of the tracker in true resolution. The green dot demarcates the moving tip of the animal. In the inlay the larvae are magnified to comparable sizes to show the spatial resolution. (A) Arena of 42.5 cm×42.5 cm; the size of a third instar larvae is 25 pixel per larval length. No automatic head recognition is possible. (B) Arena of 25 cm×25 cm; the size of a third instar larvae is 40 pixel. In about 60% of all frames the head can be identified. (C) Arena of 13 cm×13 cm; the size of a third instar larvae is 75 pixel. In 98% of all frames the head can be recognized. (d) Arena of 6 cm×6 cm; the size of a third instar larvae is 170 pixel. (E,F) Two 170 pixel images demonstrating the high resolution of FIM. Several inner structures are indicated. (G) Screen shot of a movie taken with illumination by 470 nm LEDs, seven larvae are shown, two of which express daGal4 driven GFP.