1. | Each eye contains about 920 ommatidia arranged in approximately 40 nearly horizontal rows (Figs. 5, 6). |
2. | There is an acute zone ( visual streak ) of ±5° around the eye equator with high vertical resolution (Fig. 9). |
3. | The horizontal interommatidial angle ![Delta](/content/V638V438222250H1/xxlarge916.gif) oh varies little with altitude and is in the frontal parts of the eye equal to the (horizontal) interrhabdomere angle ![Delta](/content/V638V438222250H1/xxlarge916.gif) rh (Fig. 10). |
4. | Above and below the visual streak the eye is adapted to the perception of relative height or depth constancy (Fig. 13). |
5. | Reconstruction of the viewing directions of the rhabdomeres in the visual streak reveals that characteristic groups of rhabdomeres in different ommatidia coincide in their receptive fields . Optical prerequisites for two types of neural superposition can be found: one of medium neural summation but highest sampling frequency, the other of highest neural summation at the cost of resolution (Fig. 11). |
6. | The correspondence of the limits of resolution due to diffraction and finite sampling frequency is discussed. |