Development of Forest Survey Method by Combining GPS and Laser Ranging Instrument

1. 利用GPS和激光测距仪直接测量磁北纬在进行森林测量以确定点的地理坐标时，通常使用三角测量点或其他授权点。但是这样的点在森林地区是稀疏分布的。如果知道该地区的磁北纬，即使通过罗经测量也很容易确定地理坐标。在本研究中，我们开发了一种利用GPS和激光测距仪（LRI）直接测量磁北纬的方法。选取北海道东京大学森林和千叶大学森林作为研究领域。在北海道，我们发现该地区的磁北纬与所说的相差1度或更多。此外，在大学森林区域内也存在近1度的差异。基于GPS和激光测距仪的林分配置制图方法研究在千叶东京大学林分配置制图试验地进行了LRI林分配置制图方法的试验研究。结果表明，与传统方法相比，lri辅助制图更简单、快捷、高效。测量时间缩短到一半以下，并且只需要两个人进行测量。使用电子表格类型的软件，如Excel和Lotus 1-2-3，测量数据的后处理也很容易。利用GPS定位和该地区的磁北纬（用上述方法测量），可以很容易地在地理坐标上绘制出站位布置坐标。这意味着我们可以很容易地确定森林中任何一点的地理坐标。森林地理信息系统的实施将需要这类信息作为基础数据。我们相信我们的方法将有助于实现这一目的。

1. Direct measurement of magnetic north declination using GPS and Laser Ranging InstrumentTo carry out a forest survey to identify geographic coordinates of the point, triangulation point or other authorized points are usually used. But such a points are sparsely allocated in forest area. If magnetic north declination of the area is known, it is easy to identify geographic coordinates even by the compass survey. In this research, we developed a direct measurement method of magnetic north declination using GPS and Laser Ranging Instrument (LRI). Tokyo University Forest in Hokkaido and University Forest in Chiba are selected as research field. In Hokkaido, we found magnetic north declination of the area is different for 1 degree or more then it is said. Also we found that there are almost 1 degree difference within the University Forest teritory.2. Study on stand disposition mapping method using GPS and Laser Ranging InstrumentExamination of stand disposition mapping method using LRI are carried out in a expermental plot of the Tokyo University Forest in Chiba. We found that LRI-aided mapping is much easier, faster and efficient then traditional method. Measuring time was reduced to less than half, and also only two person were needed for measurement. Post processing of measurement data is also easy by using spread-sheet-type software such as Excel and Lotus 1-2-3. Stand disposition coordinates are easily plotted on geographic coordinates, using GPS positioning and magnetic north declination of the area (measured by the method developed above). It means we can easily identify the geographic coordinates of any point in the forest. Implementation of forest GIS will require this kind of information as the basic data. We believe our method will contribute to such a purpose.