This paper describes the actual experiments of the error propagation and studies of analytical photogrammetry using the simulation method in which we can find the causes of the errors. These studies and the results give the valuable data which are very effective for systematically controlling the errors in aerial triangulation. The main contents in my paper are as follows:
1. Dose the scale errors in the successive models in the form of normal distribution appear when the observation errors propagate in the form of normal distribution?
2. In what form does this scale error propagation in the actual model appear?
3. When the causes of the scale error propagation are found, is the evaluation standard determined normally?
4. What degree of influence is there from the constant errors?
I have done several experiments using the simulation method technique to solve the complicated error propagation of aerial triangulation which is the effective means to research the relations between cause and effect. In this paper, the studies have concentrated on the following points of simulation experiments.
(1) The first part describes how we can produce the soft program of the simulation experiment.
(2) The second part is the method propagating the errors in the simulation models and the kinds of errors.
(3) The final part is the most important; that is the analyzing and evaluation of the influence of the errors in the models to take advantage of control during actual work.
From the above-mentioned points, it is said that these studies are a very important development in the field of controlling and managing aerial photogrammetry and especially in the case of error propagation, we can clearly find the causes of the errors and steps and parts of errors generated when we use these techniques.

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Several authors have made the observations on the phenomena of the snow avalanches, the snow creeps, the snow glides in the heavy snowfall regions, North Japan. However, these were investigations without the snowfall of the face of slope.
In this paper the authors propose to utilize the terrestrial photogrammetric method in order to make clear the distributional tendency of the snowfall on the face of slope which was the first time to take advantage of such a method in Japan.
The authors emphasize that this method is useful for measuring the distribution of the snowfall on the face of slope.
According to the authors' observation, the berm seems to play an important role in the prevention of gliding snow.

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Most of the specifications in survey contract in Japan have some vagueness on the accuracy of contours. Usually they give the half of the contour intervals 0.5Δ as the tolerance of contouring accuracy, without further comments on the term“accuracy”. Another kind of specifications, those in USA, for example, describes that“90% of the errors of spot hight interpolated from contour lines should be less than 0.5Δ”.
After comparison of three two kinds of descriptions, the latter seems more practical and reasonable, and is equivalent to assume the standard deviation of contouring as about 0.30Δ”. Further detailed analysis considering the errors of adjacent contour lines simultaneously resulted the similar conclusion but with some spread of standard deviations, 0.25Δ-0.36Δ, for example.
Finally the contouring accuracy in photogrammetry may have different characters from that in plane table surveying, by which contours are observed on the terrain in nearly horizontal directions, while by the former procedure the observations are done from the above in the air. The numerical constants α and β in the Koppe's formula are compared to examine the difference in both procedures. The ratio β/α in photogrammetry shows smaller values than those in plane table surveying from the experimental work.
It is tried to give the ratio β/α an interpretation as the tangent of observing direction, based on the modified Koppe's formula (24) . As an example, observing directions in photogrammetry are 19°-46° from the nadir lines and 70°-85° in plane table survey.

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This is preliminary and essential report on four-dimensional photogrammetry. We continue the discussion both view points; one is a new concept on one-to-one correspondence between object and image space, and the other a new concept on dynamic stereoscopy.
These concepts are created through the practical problem to find time-serial coordinate values (X, Y, Z, T) of the rolling stone locus on the steep slope or cliff by 35mm high speed movies. We can obtain good results on both the workability and its precision; the position accuracy was ±0.1m & the time accuracy was ±0.02 second from about 100m distance.

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