This error is reported when more than 100 observer features in the input observer feature class are found with either invalid geometry or invalid observer attributes (for example, the observer offset field has null values). This error is similar to error 010454, except that error 010454 is reported when the number of invalid observer features is less than 100.
Check that all the input features have valid geometries. Repair the features that have bad geometries or remove them. Check that all the input features have valid observer attributes. Replace the null values with valid numeric values.