Abstract: A static and a dynamic random-dit stereogram(RDS) pair is produ- ced respectively by a microcomputerized pseudo RDS generator and displa- yed on corresponding left and right oscilloscopes, observed by two eyes respectively. 10 subjects with normal stereoscopic vision viewed by a stereoscopy and the smallest tolerant element density in which binocular fusion can produce clear perception of form in depth was determined. Three experiments were designed to determine the effect of changing spatial parameters of RDS patterns on the limitation of the element den- sity. The first was the change of pattern area for the static and the dy- namic RDS respectively. The second was the change of pattern form and the third was the change of circumference of pattern with disparity. The result indicates that binocular stereoscopic perception can tolera- te a certain limitatity of element density, changing of size and form of pattern affects tolerant element density to a certain extent. The limitati- on of tolerant element density for static RDS differs for dynamic one. The experimental result was discussed using global stereoscopic cha- racteristic and spational frequency channel.

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