A series of environmental policies in Sichuan province was executed to restore the grassland and forestland on some degraded lands after 2000. But the effectiveness on land use and cover change (LUCC) has not yet been systematically investigated. We undertook a detailed analysis about land use and cover change between 2000 and 2005 in Sichuan province. Our study mainly utilized remotely sensed data of 2005 China-Brazil Earth Resources Satellite II (CBERS II) and 2000 Landsat 5 thematic mapper (TM) data. Land use and cover change between 2000 and 2005 was visually interpreted by CBERS II with ArcInfo Workstation based on land use and cover database interpreted from TM. Then LUCC was validated by ground truth with global positioning system receivers. Our analysis illustrates that the conservation policies to restore the grassland and forestland were successful to a lesser extent. But more measures to restore the grassland and forestland of Sichuan province have to be taken further in the future.
Laser diode adopted in LiDAR (Light Detection And Ranging) onboard a small low-cost UAV (Unmanned Aerial
Vehicle - UAV) platform usually requires its carried components to be light in weight, small in volume, and specially
efficient in energy supply. A DC-DC converter and a fast switch are often applied for the traditional power supply to
drive the LiDAR system. This traditional method is not proper for application in a UAV platform. This paper provides a
novel power supply topology, which consists of two coupled coils, pulse generator circuit, and a fast switch. The power
supply topology has been designed, assembled, tested, and confirmed to generate pulse voltage of 100-300 V, up to 120
A pulse current, 50-200 μs pulse width, and 50 Hz maximum pulse frequency. The driver circuit is very simple, but could
restrain current surge efficiently. This ensures that the laser diode does not be disturbed. It is demonstrated that it is
sufficient to drive a laser diode used in LiDAR onboard UAV, and meets the requirement of weight and volume. Now the
driver has been manufactured for application in UAV-based airborne lidar sample system.
In this paper, a mathematic model for POS based bundle adjustment is introduced. The model is made up of four types of linearized observation equations. The intention of the POS based bundle adjustment is to minimizing the error between the four types of observed value and its model value. We use the Levenberg-Marquardt algorithm to achieve this purpose. Our work is supported by China 863 program titled 'airborne multiangular imaging technique in power line inspection' (AMPLI). The purpose of this program is to monitor the relative distance between the power lines and the objects beneath them with accuracy as high as 0.5 meters. A number of high-resolution images must be captured along the power lines to ensure the accuracy. Based on an automatic matching method proposed by other team members in this program, hundreds of homonymous points can be extracted in one image. About 30 to 50 images are used in one block adjustment. As a result, large number of unknowns will contribute to the minimized error, and numerous equations should be solved. So, the minimization algorithm must incur the high computational costs in the problem. Fortunately, the normal equations reconstructed from the observation equations above exhibiting a sparse block structure. Considering the sparse characteristic of the normal equation, we propose a sparse bundle adjustment method based on Levenberg-Marquardt algorithm to save computation cost. A software package is developed based on this algorithm. A comprehension test was performed to investigate the performance of the algorithm. We used a data set provided by a field experiment in Wuhan, China. It is found that our algorithm showed both high accuracy and high efficiency in the test.
This paper presents a simulated architecture of an envisioned future intelligent Earth observing satellite system (FIEOS). The proposed system is a space-based architecture for dynamic and comprehensive on-board integration of Earth observing sensors, data processors and communication systems. It is intended to enable simultaneous, global measurements and timely analyses of Earth's environment for a variety of users. This paper also reports our progress of initial research in on-board image database management, including data structure, data model, and query. The intelligence of EO satellite system lies in that common users would access data directly, and in a manner similar to selecting a TV channel. The imagery viewed would most likely be obtained directly from the satellite system. The future of this system is promising for Earth observation. Real-time information systems are key to solving the challenges associated with this innovative architecture. Realization of such a technologically complex system will require contributions of scientists and engineers from many disciplines. Hopefully, this revolutionary concept will impact dramatically how future Earth observing satellite's development in the next few decades.
With the increasing sensor development, smart sensor, advanced sensor, and intelligent sensor, especially, distributed sensors, sensor network and sensor integration are being taken into account for application of our environmental monitoring and Earth source investigation. This paper investigates the development of sensors in Earth observing (EO) satellites, analyzes the current high-resolution EO satellites and presents the direction of new imaging systems in future Earth observing satellite. The purpose of this paper is to contribute to those who are interested in knowing and keeping track of the details of the imaging system of earth observing satellites.
A novel birefringent (alpha) -BaB2O4 crystal with 40 mm in diameter, 35 mm in height has been grown successfully in our laboratory by Czochralski method. The proportion of B2O3 and BaO of starting materials, crystal cracking and the transmission spectrum of (alpha) -BaB2O4 crystal have been briefly analyzed.
Large-size sapphire crystals are grown by the temperature gradient technique. In order to address current applications, (0001)-oriented boules have been put into production and the quality is analyzed.
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