Zhang Huaiqing

Study on the dynamic monitoring and succession analysis of wetland types in Dongting Lake area

In this paper, three period times (1987, 1996, 2004) of Landsat TM remote sensing images data are chosen to monitor the main wetland types changes in Dongting Lake area. According to the main wetland types distribute in Dongting Lake area, a classification system of wetland types is build at first. Then the software of Erdas Images and Fragstats are used to process remote sensing images and statistical analysis. After comparison of landuse types, landscape pattern indices and transfer matrixes among three period times, the result is that the area of the wetland types decreased heavily, especially mudflat and paddy field from 1987 to 1996 because of the history “reclaiming the land from the lake”, but some wetland types change and trend presented a turning point around 1996, which effected by the national policy of “returning farmland to lake” launched in 1998. From 1987 to 1996, the main succession of wetland in Dongting Lake was lake water→ mudflat→ sedge land→ reed flat→forest. However, from 1996 to 2004, the natural wetland types presented the change in jumps from other various wetland types directly to forest land. The major factors influencing the wetland changes in Dongting Lake are human activities, sediment accumulation and local policies etc. Among them, the implementation of “returning land to the lake” has relieved the shrink of lake and promotes the renewal of natural wetland to a certain extent.

Study on visual simulation of stand structure from forest from map

With the rapid development of information technology and computer technology has improved; visualization technology has been widely used in various fields. In forestry, forestry visualization technology breakthrough two limiting factors in the time span and spatial scales, and increasingly become a research hotspot. If we build a virtual forest environment, forestry workers would make more convenient and intuitive, efficient management and research forest. However, visualization of the data source demanded strict, and need to be collected more data to visualization. These would be brought great difficulties to the study. Therefore, this study attempts to gain the information of the visual simulation in the random distribution of the rules for the distribution of forest structure by directly reading the files in the forest form map, and construct a visual simulation algorithm of the distributed rules.

Application analysis of laser scanning technology in trees measurement

This paper introduced the procedure of forest measurement using three-dimensional laser scanning and summarized the method of data processing by the experiment in Xiaolong Mountain of Gansu Province. The way of establishing 3D visualization model of trees using 3D laser scanning data was brought forward as well. And model accuracy was verified. The results show that the model reconstructed using this method can not only be measured with high accuracy of the tree measurement factors such as height and DBH to meet the requirements of forestry survey, but also provide multitudinous 3D models of single tree for the 3D visualization simulation of stand and landscape.

Study on visual simulation of selecting trees based on triangle in thinning

The investigation plot of Chinese fir plantation was the research object and the CCF was used for determining the growing state of forest trees. The real-time visual simulation of selecting trees based on triangle in thinning by using the C# programming language and the GDI+ technique was displayed in 2-dimensional scene. The thinning results were displayed in 3-dimensional scene by using the MOGRE technique. The reserved trees were well-distributed and the distances of them tended towards uniformity. It not only can service for selecting felled trees in scientific way, but also can offer a straightforward and efficient visual decision-making platform for adjusting forest structure, improving forest competition relation and using forestland resource sufficiently.

Research on extracting forest stand information based on 3D laser scanner techniques

The development of laser scanning technology provides a new way to make people obtain spatial information from the traditional manual to automatic. In this study, we take the FARO Laser Scanner Photon as the data obtained platform, we scanned a 10 m × 15 m plot, total 20 trees in Pinus bungeana Zucc. plantation, extract every trees data from the point cloud and measure the tree height and diameter at breast height(DBH). After make accuracy precision and correlation analysis with the measured data, it is showed that the method mentioned can be satisfied the accuracy requirement of forest investigation and can be used to measure the tree height and DBH. Compared with traditional technology, the applications of 3D laser scanning technique have a broad development space on tree measuring.

Forest Fires Simulation Based on MOGRE Particle System

Based on forest fire spread model Rothermel, visualization simulation technology combined with the actual forest region geography environment are used to dynamic real-time display fire boundary in the paper. The fire spreading model and the MOGRE particle system are combined to show the spread of forest fire process and to provide the forest auxiliary emergency decision support, which can play an important role to effectively organize and calculate the fire fighting and reduce the loss caused by the forest fire.