Mapping the last frontier
阿拉斯加是美国最不合适的最大状态。众所周知，由于其多样化的景观和寒冷的天气，旅行可能在冬季困难。在北部的国家北部，苔原辽阔，冬季Cli-Mate是苛刻的，使用冰路是流行的，需要运输资源。由于该州拥有超过20亩的湖泊的大小，因此需要清楚地了解景观，以便最佳地确定这些道路可以安全和可持续地建造的地方。经济地质局（局），德克萨斯大学奥斯汀的研究单位，旨在映射这一野生边疆的一部分，并利用Leica Chiroptera Airborble Lidar系统进行调查，更好地了解当地栖息地2014年阿拉斯加北坡。
A unique landscape
阿拉斯加北坡微型地形支持北极潮汐环境中的各种潜在鱼栖水体和湿地地区。浅层湖泊，一般来说，小于2米的深度，是该地区苔原景观的主要组成部分，在那里他们组成了总面积的大约20％。他们在日历年里只有几周内完全没有冰，所以我们计划在7月中旬开始，并于8月初结束。
The lakes’ depth, ice growth, and decay determine whether they are suitable habitat for wildlife and aquatic fauna, as well as for industrial development. Ice accumulation is assumed to be 1.5 to 2 m thick in this area, and liquid water most likely lies below in the central basins of these lakes if the water is deeper than 2 m. Survey findings were particularly important because they would reveal lakes deeper than 2 m, suitable for building ice roads, but with potential fish habitat. Findings were also expected to assist other environmental and hydrological assessments in the area.
“With thousands of lakes – with varying turbidity levels – scattered throughout the survey area and challenging weather conditions that limited the airborne survey activities, this was certainly not an easy task,” said John Andrews, a research scientist, who was responsible for ground truthing and overall logistical support. “With airborne LiDAR surveying, though, we were able to obtain very detailed and precise topographic and bathymetric data in areas where traditional survey methods would not be feasible.”
Flying with double the scanning power
A total of 95 lines were flown to cover the entire survey area, where line numbers increased in the westerly direction. The average flight line was approximately 50 km long. To ensure complete coverage, the flight line spacing was set at 160 to 180 m, where the ground laser swath footprint was calculated to be 280 to 290 m wide. To compensate for the changing ground elevation (30 m in the north, 95 m in the south), atmospheric pressure was monitored during flights to maintain a constant flight altitude and swath above the ground.
The Chiroptera uses two LiDAR scanners to acquire topographic and bathymetric data. Data from the topographic LiDAR (red wavelength) was fired at 300 kHz and used to acquire high-resolution 3-D positional data on vegetation height and earth topography. Data from the bathymetric LiDAR (green wavelength) was emitted at 35 kHz and used to determine water related statistics; such as depth, volume and area size. We also collected colour-infrared and natural-color imagery at 400 m and 1700 m, respectively, for visual reference and ortho-rectification purposes.
“The technological cornerstone of this project was the Chiroptera airborne LiDAR and imaging system,” said John Hupp, a research scientist from the Bureau, who was responsible for field data processing and system calibration. “Simultaneously collecting high resolution imagery with the LiDAR data allowed us to easily discriminate water bodies, vegetation characteristics, wetlands, and uplands, saving us time and costs compared to any other conventional type of surveys.”
For both LiDAR scanners, the average vertical offset was measured at less than 1 cm, while the standard deviation was calculated at approximately 3 cm compared to the ground control points collected at Deadhorse airport runway pavement. Calibra-tion procedures were applied to both scanners individually, where average roll and pitch biases were measured to be less than 2.6 cm.
“我们也检查和纠正任何明显的激光雷达system calibration errors caused mostly by incorrect inertial navigation system (INS) rotation angles of roll, pitch, and yaw. These errors can be detected through analysis of adjacent and op-posing LiDAR strips,” said Hupp. “In theory, if no rotational misalignments are pre-sent, LiDAR points registered from different strips should match each other seam-lessly on an unobstructed surface; although not expected to have perfection, we can achieve very close results in practice.”
Faster, more accurate data analysis
Leica Lidar Survey Suite LLSS V2.09用于将原始数据文件转换为Indus-Try-Standard LAS1.2进行输出。由于LAS数据集采用二进制格式，因此可以快速轻松地访问信息，以便进行分析或可视化目的。两个扫描仪的数据集都均铺升到1 x 1公里，以简化数据查看和分析的计算要求。结果，我们在调查区域生成829个瓷砖，每个图块都包括每个方向的20米缓冲区，以生成用于映射目的的无缝的1 M数字高度模型（DEM）。
The deepest water body was calculated at 3.5 m. Of all 4,697 water bodies analysed, 3,837 (81.7 percent) were classified as shallow or very shallow, with measured depths of less than 1 m. Only 4.6 percent (216 total) of the water bodies had depths that exceeded 2.0 m. The average depth of all water bodies was calculated at 0.67 m.
总共3,014个水体（64.1％）含有少于1,000立方米的水量，而1,683湖湖泊计算出超过1000m3的水量（35.9％）。分析的所有水体的平均体积在分析的所有水体的12,771m3（3,373,741Al）下进行计算。
A unique landscape
阿拉斯加北坡微型地形支持北极潮汐环境中的各种潜在鱼栖水体和湿地地区。浅层湖泊，一般来说，小于2米的深度，是该地区苔原景观的主要组成部分，在那里他们组成了总面积的大约20％。他们在日历年里只有几周内完全没有冰，所以我们计划在7月中旬开始，并于8月初结束。
The lakes’ depth, ice growth, and decay determine whether they are suitable habitat for wildlife and aquatic fauna, as well as for industrial development. Ice accumulation is assumed to be 1.5 to 2 m thick in this area, and liquid water most likely lies below in the central basins of these lakes if the water is deeper than 2 m. Survey findings were particularly important because they would reveal lakes deeper than 2 m, suitable for building ice roads, but with potential fish habitat. Findings were also expected to assist other environmental and hydrological assessments in the area.
“With thousands of lakes – with varying turbidity levels – scattered throughout the survey area and challenging weather conditions that limited the airborne survey activities, this was certainly not an easy task,” said John Andrews, a research scientist, who was responsible for ground truthing and overall logistical support. “With airborne LiDAR surveying, though, we were able to obtain very detailed and precise topographic and bathymetric data in areas where traditional survey methods would not be feasible.”
Flying with double the scanning power
A total of 95 lines were flown to cover the entire survey area, where line numbers increased in the westerly direction. The average flight line was approximately 50 km long. To ensure complete coverage, the flight line spacing was set at 160 to 180 m, where the ground laser swath footprint was calculated to be 280 to 290 m wide. To compensate for the changing ground elevation (30 m in the north, 95 m in the south), atmospheric pressure was monitored during flights to maintain a constant flight altitude and swath above the ground.
The Chiroptera uses two LiDAR scanners to acquire topographic and bathymetric data. Data from the topographic LiDAR (red wavelength) was fired at 300 kHz and used to acquire high-resolution 3-D positional data on vegetation height and earth topography. Data from the bathymetric LiDAR (green wavelength) was emitted at 35 kHz and used to determine water related statistics; such as depth, volume and area size. We also collected colour-infrared and natural-color imagery at 400 m and 1700 m, respectively, for visual reference and ortho-rectification purposes.
“The technological cornerstone of this project was the Chiroptera airborne LiDAR and imaging system,” said John Hupp, a research scientist from the Bureau, who was responsible for field data processing and system calibration. “Simultaneously collecting high resolution imagery with the LiDAR data allowed us to easily discriminate water bodies, vegetation characteristics, wetlands, and uplands, saving us time and costs compared to any other conventional type of surveys.”
For both LiDAR scanners, the average vertical offset was measured at less than 1 cm, while the standard deviation was calculated at approximately 3 cm compared to the ground control points collected at Deadhorse airport runway pavement. Calibra-tion procedures were applied to both scanners individually, where average roll and pitch biases were measured to be less than 2.6 cm.
“我们也检查和纠正任何明显的激光雷达system calibration errors caused mostly by incorrect inertial navigation system (INS) rotation angles of roll, pitch, and yaw. These errors can be detected through analysis of adjacent and op-posing LiDAR strips,” said Hupp. “In theory, if no rotational misalignments are pre-sent, LiDAR points registered from different strips should match each other seam-lessly on an unobstructed surface; although not expected to have perfection, we can achieve very close results in practice.”
Faster, more accurate data analysis
Leica Lidar Survey Suite LLSS V2.09用于将原始数据文件转换为Indus-Try-Standard LAS1.2进行输出。由于LAS数据集采用二进制格式，因此可以快速轻松地访问信息，以便进行分析或可视化目的。两个扫描仪的数据集都均铺升到1 x 1公里，以简化数据查看和分析的计算要求。结果，我们在调查区域生成829个瓷砖，每个图块都包括每个方向的20米缓冲区，以生成用于映射目的的无缝的1 M数字高度模型（DEM）。
The deepest water body was calculated at 3.5 m. Of all 4,697 water bodies analysed, 3,837 (81.7 percent) were classified as shallow or very shallow, with measured depths of less than 1 m. Only 4.6 percent (216 total) of the water bodies had depths that exceeded 2.0 m. The average depth of all water bodies was calculated at 0.67 m.
总共3,014个水体（64.1％）含有少于1,000立方米的水量，而1,683湖湖泊计算出超过1000m3的水量（35.9％）。分析的所有水体的平均体积在分析的所有水体的12,771m3（3,373,741Al）下进行计算。
“Chiroptera的先进技术提供了准确，细致的，经济效益的结果，允许分析世界偏远地区的微地形和碱性的FEA-TURE，”安德鲁斯说。“各种形状和尺寸 - 河流环境，湿地和高地，山丘和平坦区域以及所有其他地形特征的水体 - 被播放并迅速准确地分析。”
Written by Kutalmis Saylam
Ota yhteyttä
Täältä löydät paikalliset yhteystiedot Leica Geosystemsistä myynnistä, tuesta ja huollosta.
Täältä löydät paikalliset yhteystiedot Leica Geosystemsistä myynnistä, tuesta ja huollosta.