Mapping South Africa with twice the performance

Author:Penny Boviatsou

90多年前，农村发展与土地改革部（DRDLR）的组成部分国家地理空间信息（NGI）开始建立综合调查系统并提供南非广泛的地图覆盖范围。

NGI, is also known as the national mapping agency of South Africa, has the largest and most extensive archive of aerial photography and imagery dating back to 1926 with numerous national coverages. The imagery has evolved significantly over time, and, since 2008, all imagery is acquired with high resolution digital sensors in both colour (RGB) and colour infra-red (CIR).

In 2008, NGI decided to acquire their own Leica DMC I airborne camera system and appoint a service provider to operate the system on its behalf. Geospace International, a leading aerial photography service provider in Africa, successfully tendered and has been appointed by NGI to operate DMC I up until 2016. Geospace International also acquired its own DMC I in 2008 and used both systems for the acquisition of most of the imagery captured for NGI’s national mapping programme.

The mapping program started in 2008 and the aim was to cover the whole country (1.2 million square kilometres) every three years at 50 centimetres Ground Sampling Distance (GSD) until the end of 2016. In 2017, NGI decided to start a new cycle of acquisition at 25 cm GSD covering the country. The demand for higher resolution imagery by the users of the data led to the change in resolution.

NGI使用数据来产生1：10,000正射原，每三到五年用25 cm GSD覆盖南非。正射原型用于更新1:50的地形图。正骨动物也无需向南非公民和需要用于其GIS或其他应用程序的公司提供任何费用。

A unique solution for wide-area mapping

从NGI到2017年以来的25厘米GSD图像覆盖南非的新方向，Geospace International决定购买新的Leica DMC III airborne digital camera, based on all new CMOS technology specifically engineered for airborne applications. As part of the Leica RealWorld large area airborne imagine bundle, this sensor combines the world’s largest single frame with the most efficient post-processing workflow, HxMap, crucial for a project as such. This solution delivers unprecedented image quality and the unsurpassed geometric accuracy of a monolithic sensor, which enables Geospace International to perform the new 25 cm GSD acquisitions with the latest technology.

“The complete installation of the Leica DMC III took only three days. Our goal was to acquire 25 cm GSD imagery at approximately the same flying height as previously done with the 50 cm GSD projects using the Leica DMC I, resulting in roughly the same cost per job as before. The Leica DMC III allowed us to do this,”Geospace International主任Bernhard Jacobs说。

一旦Geospace International收集了NGI的25 cm GSD RGB和CIR图像，将校准图像以及后处理后的GPS/INS数据提供给NGI。然后，南非国家地图机构使用HEXAGON GEOPSOTIAL IMACETRATION IMACETRATION套件进行了空气三角剖分，高程捕获和最终正际创造的过程。bob综合app下载bob体育报道该软件提供了大量的摄影测量法和生产映射工具，包括来自空中和卫星图像的项目创建，方向和三角剖分。

Twice the performance

Geospace International is operating an Aero Commander 690B twin turbine aircraft. The team consists of two pilots and two camera operators.

“The light-weighted Leica DMC III allowed us to add additional 1.5 hours of flying time per day. Previously, we had to return to refuel, having an impact on cost and time,”said Jacobs.

The additional fuel allows Geospace International to cover more areas in a day than before. With an average 5.1 hour of flying time per day and high performance, processing of HxMap, the DMC III表演翻了一番。

“我们现在可以飞相同的工作之前空运5点0 cm GSD with the Leica DMC I, at 25 cm GSD with the Leica DMC III, with 5 to 10 percent additional flight time. In mountainous areas, we fly the same amount of flight lines to cover the area at 25 cm GSD as we would with the DMC I at 50 cm GSD.

“新的DMC III在整个块上具有更好的总体辐射测定法和更均匀的质量。GPS/IMU结果给我们留下了深刻的印象。”said Jacobs.

Unprecedented productivity

Geospace从2017年7月至11月的25厘米GSD覆盖了240,000公里以上的240,000公里，近50,000次发行版，并且提前了三个月。该公司的目标是每三到四年继续为NGI覆盖南非的NGI图像。

“我们会向空中调查行业中的任何人推荐Leica Geosystems产品和解决方案bob综合app下载，因为员工提供的质量，出色的支持以及使用系统时的总体耐用性和长期使用，没有问题，”said Jacobs.