Contour map has not enough information to support the road design or site location in this sophisticated age. To supply more information, orthophotomap has been, therefore, developed by adding the pictorial information to the contour lines. However, orthophotomap is rather expensive and unable of stereoscopic view. On the other hand, aerial photographs can be seen stereoscopically, while they has not uniform scale.
In order to improve these inconveniences, a new technique has been developed in this study to form the digital terrain model and the digital photomap by using terrain data and pictorial data measured in the mesh system on the aerial photograph. This technique enables the conversion of digital terrain model with pictorial information in both ways between photo-coordinate system and ortho-coordinate system.

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The results which were obtained from snow crack measurements from airphotos (1/10, 000) and topographic maps (1/10, 000) are as follows;
1. There is a direct relation between slope length (L) from the foot of a slope to crack and average inclination of a slope (θ) . The formula is L^1/2.3 sinθ=2.9.
2. The crack width distribution obeys the log normal distribution. The crack width is related to the slope width. The small scar width distribution in Kure region is similar to the snow crack distribution. The distributions of the snow cracks under different conditions are almost constant.
3. The shapes of snow cracks are similar to one another. The width of a crack is twice as large as the length along the slope.

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