Benefits of Sweeping Airborne Cameras

TheA3边缘数字映射系统是一种能够从高空高度产生高分辨率和准确图像的扫描相机系统，因此可以快速有效地进行调查。该系统适合捕获城市地区以及人口稀少的地产。2014年，它用于俄罗斯的两个项目：圣彼得堡的3D映射和北方森林的地图。

VisionMap’s A3 dual-camera system, introduced in 2008, obtains vertical and oblique views at the same time by sweeping two cameras across track simultaneously. The sweeping allows generation of a field of view (FOV) of over 100 degrees. The centre part of the total frame – up to an FOV of 40 degrees – is suited for orthoimage generation. The single frames captured outside this FOV range, i.e. the frames towards the end of the sweep, are de facto oblique images. Five years after the launch of theA3，VisionMap引入了A3边缘，旨在增加较高地面样品距离（GSD）的每小时捕获的面积。有关A3 Edge及其与其他系统的比较的进一步描述，请参见M. Lemmens发表的文章188金宝搏特邀2014年[1]。加上A3 Lightspeed软件，A3 Edge提供了完整的端到端映射解决方案。A3 Lightspeed自动执行空中三角剖分（AT），并从A3图像中产生正面模拟，立体声对和数字表面模型（DSM）。随着映射公司从事越来越188asia备用网址多的项目，该软件必须越来越多地处理成千上万的图像，这是成功的。完整的A3数字映射系统符合所有行业标准。

Saint Petersburg

该项目旨在orthoimag的创建ery of the entire territory of Saint Petersburg and the preparation of vertical and oblique images for stereo and/or mono interpretation and 3D city modelling. Colour (RGB) vertical and oblique images were captured by crisscross flight lines spanning an area of 2,007km². During 11 hours of flight, 450,000 vertical and oblique images were captured. The challenges included: restrictions on the minimum flight altitude; the need to acquire vertical and oblique images for orthoimagery and 3D city modelling; and year-round scarcity of good flying weather. Table 1 shows the main survey parameters. The long focal length allows theA3 Edge飞在高海拔地区,同时提供一个嗨gh GSD and high productivity. The simultaneous collection of vertical and oblique imagery is beneficial for 3D city modelling. Firstly, all vertical and oblique images were simultaneously adjusted by the A3 LightSpeed AT module resulting in accurate orientation parameters. Next, the vertical images were combined with a previously created DSM for orthoimagery creation. The resulting imagery was used for the creation of a 3D model of Saint Petersburg.

所有地图产品都符合1：2,000映射的准确性要求。在矫形图中的创建和矫形成像是自动完成的，并花了一个操作员15天。相比之下，Baltaeroservice在2011年使用中型摄像头捕获了同一区域，并使用TALCA 4.0摄影测量软件处理图像。五个运营商六个月才完成这项工作。图1显示了该项目期间捕获的垂直和斜图像的两个示例。

	St. Petersburg	Forest
Flight altitude	4,050m (13,300ft)	5,400m (17,700ft)
GSD	10厘米	14cm
向前重叠	60%	55%-70%
Side overlap	80%	55%-70%
Side oblique overlap	30％
飞行线之间的距离	1,500m	3,000m
最大倾斜角	55°
地面速度	140-150knot	150 knot

Table 1,圣彼得堡和森林地区的调查参数

森林

The Russian Forest Agency commissioned a project to cover large forest areas by aerial survey and to create colour (RGB) and colour infrared (CIR) orthoimagery. Russia is covered by 8 million square kilometres of forest, and its inventory – using satellite imagery – and its taxation by ground survey is done annually. The high GSD of the A3 Edge and its high RGB and NIR image quality enable the labour-intensive ground survey for taxation to be replaced by stereo-photogrammetric inventories. Images with a GSD of 14cm were captured covering an area of 33,490km²within 48 hours. Table 1 shows the main survey parameters and Table 2 the main characteristics of survey, area and processing times. The orthoimagery, created using an existing DSM, was delivered in 4 bands (RGB and NIR) with a GSD of 30cm. The processing was completed within 52 days. The latest version of LightSpeed supports up to 250,000 images in a single block. With a forward/side overlap of 55%/60%, the images in the block may cover up to 55,000km². Treating such extensive areas as a single block provides high homogeneous accuracy and eliminates manual processing of adjacent blocks. Other powerful features are automatic tie point creation, even where the forest is dense, and automatic creation of cut lines. Multiple overlaps between images as well as many tie points ensure that AT generates high-accuracy results. High visual quality of the end products is obtained through automatic adjustment of brightness, colour and contrast, and through haze removal. The end products delivered are RGB and CIR super large frames mainly used for stereo interpretation for taxation purposes and stereo mapping and RGB and CIR orthoimagery (Figures 2 & 3).

Province (Oblast)	区域[公里2]	Distance from base [km]	调查时间[HR]	总飞行时间[HR]	处理[Day]
Novgorodskaya (two areas)	10,780	250/330	16.0	36.1	14
Pskovskaya 1	1,290	200	2.4	3.8	5
Leningradskaya	4,660	170	6.4	10.9	8
卡雷利亚	8,750	550	11.9	25.7	12
Pskovskaya 2 (two areas)	1,110	340/320	2.1	5.8	5
Archangelskaya	6,900	530	8.9	20.6	8
Total	33,490		47.7	102.9	52

Table 2, Characteristics of survey, area and processing of forest areas.

Baltaeroservice

Based in Saint Petersburg, Baltaeroservice has been active in the mapping market for 18 years, mainly in the northern part of Russia. The company specialises in aerial surveying and mapping of roads, railways and other linear structures and large forest areas. Baltaeroservice owns a Cessna P210 aircraft, has access to other aircraft and has used various aerial survey and mapping technologies over the years. The company is seeing a steady increase in demand for up-to-date map products, for high-resolution, vertical and oblique images of urban areas, and for regular mapping of extensive areas.

Figures:

Figure 1, A3 Edge vertical and oblique images (inset); Peter and Paul Fortress (left) and Saint Isaac's Cathedral.

Figure 2, CIR orthoimage and RGB image (inset) of dense forest area.

图3，伐木区的CIR矫正图。

进一步阅读

[1] Lemmens，M。（2014）数字斜空机（2） - 特征和系统的调查，188金宝搏特邀, 28:5, pp. 20-25.

Authors

Dr Yuri Raizmanholds an MSc and a PhD – both in photogrammetry – from institutes of Moscow, Russia, and has over 35 years of experience in the field. He has published 60 papers and prepared over 20 national technical instructions, standards and specifications. Before joining VisionMap as chief scientist in 2008, he worked as chief of photogrammetry and remote sensing and national GIS manager at Survey of Israel.

亚历山大·马加沙克（Alexander Magarshak）, CTO of Baltaeroservice since 2009, graduated in applied geodesy from the Leningrad Mining Institute, Russia. He has worked in the field of geodetic support of exploration work in the Far East (Magadan region). As an engineer instructor, he has worked and trained professionals in Mongolia. He has been engaged in digital photogrammetry since 2005.