A technique observing contour lines of an object by the use of moiré is developed. Shadow of an equispaced plane grating is projected onto an object by a point source and observed through the grating. The resulting moiré is a contour line system showing equal depth from the plane of grating if the light source and the observing point lie on a plane parallel to the grating. A technique to wash away the unwanted moiré and the results of applications are described.

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Our observation of a dye diffusion (in which uranin was used) was carried out at Tokyo Bay on October 13, 1968. This paper deals with the state of a dye diffusion as revealed by the measurement of the photo density of a dye patch with a photodensitometer.
Our previous study of dye diffusion in the ocean (carried out in 1965 and 1966) was based on two widely held assumptions: one-that dye density is inverlsey proportional to the area of the dye patch; two-that dye density is homogeneous in a dye patch. In our most recent study we found that the density of a dye patch could be determined by measuring the density of the distribution with a photodensitometer. Further, we found that the relation between photo density and dye density corresponded to the equation logY (mV) =alogc+b. Using this equation, we estimated the dye density from the photo density of the dye patch. Then, we calculated the coefficient of dye diffusion by using formula (3) .
In another case, we assumed that the density of a dye patch was homogeneous. In this case, we estimated the coefficient of the dye patch by using formulas (4) and (5) .
In comparing the results of these two coefficients we found that the 1st coefficientK_Xequaled 10⁴-10⁶andK_Yequaled 10³-10⁴. (These figures are rather large.) In the second coefficientK_Xequaled 10³-10⁵and K_Yequaled 10¹-10³.
Theoretically, the former method is superior to the latter; but the data obtained from the former was not quite satisfactory because of the fact that it was based on our assumptions.
Further studies will have to be made before these assumptions can be proven to be absolutely correct. When these studies are made, care will have to be taken to insure that the scale of turbulence is taken into consideration.

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A procedure to form a strip digital terrain model has been developed by using terrain points located on strip meshes, composed of two dimensional array along alignment and perpendicular to alignment. The strip digital terrain model has the following practical merits.
(1) It is able to interpolate height of any point so efficiently by using a small amount of input data.
(2) It is not necessary to remesure the terrain points even if a part of route is modified.
(3) Fore-processing to measure terrain points and the subsequent processing for design can be executed automatically.
(4) It is very effective for automatic calculation of earth works in highway design.

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Earth design such as land levelling for a new town needs a large amount of earth works. In case to modify the original land, or natural circumstances, various effects caused by quantitative and qualitive change of surface should be considered from wide view of points.
This paper introduces a procedure to find an initial solution which type of earth design could be possible or preferable, and to evaluate the solution both numerically and visually.

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In our laboratory we have the so-called camera calibrator made by Nippon Optical Company Ltd., by which we can measure the several optical characteristics of the aerial camera under such a condition as equipped with lens.
In this report discussed are the results of both distortion and the resolving power of some two cameras which were measured by using this calibrator.

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