Calibrating view angle and lens distortion of the Nikon fish-eye converter FC-E8

Recently, an inexpensive digital camera that can equip with a fish-eye converter lens, FC-E8, has been available from Nikon. The converter has more than 180° view angle and lens distortion. The objectives of the present study were to develop a procedure for calibrating the view angle and lens distortion of the fish-eye converter, and to examine the effect of the calibration on light environment estimates. Based on unpublished data provided by the Electric Image Technical Center of Nikon, a 12-order poly-nomial expression for the calibration was derived. The expression enabled us to calibrate the view angle and lens distortion for all selectable resolution digital images. Using a Nikon Coolpix 990 digital camera with the fish-eye converter, 105 hemispherical photographs were taken in 15 stands, and then the canopy cover and weighted openness were measured as the light environment estimates. The calibrated estimates were significantly higher than uncalibrated ones, but the differences were comparatively small, with the average differences being 0.658% for canopy cover and 0.344% for weighted openness. A strongly positive correlation between calibrated and uncalibrated estimates was observed. Both slope and intercept of the regression lines of the calibrated estimate against the uncalibrated one were significantly different between canopy cover and weighted openness, suggesting that the calibration effect would be different among light environment estimates. In conclusion, we should pay attention to the view angle and lens distortion of the fish-eye converter in estimating light environments using the Coolpix digital camera.     

基于双目立体视觉SLAM的林下实时定位

[目的]在林下环境中受到树木冠层的遮挡,易造成全球导航卫星系统卫星信号失锁,不能满足林下实时定位的需求.本研究引入双目立体视觉SLAM技术,在移动过程中根据周围环境中路标点的位置变化实时确定传感器的空间位置和姿态,以期在林下环境中达到实时定位的目的.[方法]实验过程中使用双目相机按照10 Hz的采集频率对3块边长为40...     

基于GSM网络的实验室安防报警系统设计

介绍了一种基于GSM网络的实验室安防报警系统,阐述了该系统的结构及其软硬件设计.报警系统采用GSM短信模块来发送接收短信,从而实现对实验室安全的监控.该系统结构简单、安装调试容易、使用方便.     

基于Photoshop软件测量植物叶面积的白纸背景法

运用叶面积和背景白纸面积的比等于叶面积和背景白纸所占的像素比的原理,将待测叶片平铺在白纸背景上,利用手机相机拍摄图像,在Photoshop CS5软件上处理后分别得出叶片和白纸的总像素,最后计算出叶片面积。通过和winRHIZO系统测量得出的叶面积相比较,测量误差为-0.889%~0.632%,变异系数在0.51%以内。与其他测量叶面积的方法、或相同原理不同参照物的测量叶面积方法比较,白纸背景法具有使用器材便携易得、操作简单、可大批量测量、精确度高等优点,在林业、农业、园艺等领域具有很强的应用性和实用性。     

An irrigation control system with a web-based interface for the management of Eucalyptus planting stock in a nursery

Efficient nursery irrigation is a key factor for the production of high-quality forestry planting stock. Conventional timer-based irrigation systems used by most forestry nurseries have some drawbacks that, if not properly managed, can lead to over-irrigation and water wastage, leaching of nutrients and contribute to increased incidences of pests and/or diseases. A practical method to accurately measure media water content and control irrigation more carefully could prevent some of these issues. To evaluate the potential use of an automated irrigation system, commercially available Decagon EC-5 dielectric soil water content sensors were laboratory-calibrated against the gravimetric method using coir/pine bark/vermiculite, coir/perlite and pine bark media to measure water content of nursery seedling containers. Using Eucalyptus dunnii seedlings raised in polystyrene seedling containers to test the irrigation system, a datalogger was programmed to control irrigation for low (0.22–0.26 m³ m^?3), medium (0.26–0.32 m³ m^?3) and high (0.32–0.41 m³ m^?3) watering treatments. The measurements were displayed in near real-time using a web-based system, which allowed for system checking and from which data could be downloaded. The Decagon EC-5 sensors were successfully calibrated for all media (R² > 0.97) and provided a better estimation of media water content than the manufacturer-supplied calibration equation better-suited for soils. The automated irrigation system effectively maintained the specified media water content for E. dunnii seedlings. The high watering treatment seedlings had the highest growth rates, although this treatment also had increased leaching of nutrients. By contrast, the low watering treatment seedlings showed the lowest growth rates, although these seedlings seemed to be more robust and tolerant of water stress. This study showed that the automated irrigation system, based on measurements of the media water content, can be successfully used in scheduling irrigation for Eucalyptus seedlings, leading to potential water savings.     

Development of a monitoring system for guided circular saws: an experimental investigation

ABSTRACT

Lack of a monitoring system for guided circular saws marks one of the most critical machines in sawmills as a production bottleneck. Monitoring systems are being researched and developed for machine tools, especially for the metal cutting industry; but there are limited studies on the development of monitoring systems for circular saws in wood manufacturing process. In this study, sensors with the possibility to indicate sawing deviation were chosen that could be mounted in or on the saw guides. The sensors were: a microphone, an accelerometer, temperature sensor, an acoustic emission (AE) sensor, and a newly developed displacement sensor. A load cell was used to measure the lateral force on the guides. The outputs from these sensors were compared to the standard deviation of the board surface measured at the top of the cut. The signals from the displacement sensor, microphone, accelerometer, guide force sensor, and AE senor had no correlation to changes in the sawing deviation as measured by the standard deviation at the top of the board. Under laboratory conditions, the sound level and the AE signal did indicate the beginning and end of the cut. It was found that blade temperature is a good indicator of saw cutting performance. A newly developed temperature sensor can provide accurate temperature of the saw during cutting. The sensor can be used for measuring the rate of heating to cooling over time which can be used as a monitoring system to detect if there is any issue in the system.     

智能监视系统与高温分布式检测的光纤传感器在燃煤电厂中的应用与发展

介绍了当前智能光纤传感器的研究及应用情况,利用智能光纤传感器可以实时监控火力发电厂锅炉炉膛温度;最令人感兴趣的是对燃气、燃煤或燃油锅炉炉膛温度的估计,这对从源头上评估和控制污染物(例如氮氧化物)是非常有利的。因此利用智能分布参数估计配合光纤传感系统可以更好的检测炉膛温度,以反馈的方式来提高燃烧效率。     

0.5M分辨率航摄数字影像数据在森林资源规划设计调查中的应用

以0.5 M分辨率航摄数字影像数据为基础,结合以往调查设计及经营资料,对森林资源规划设计调查小班的部分因子进行判读,探讨高分辨率航摄数字影像数据在森林资源规划设计调查中的应用,结果表明:利用0.5M分辨率航摄数字影像数据进行小班因子判读,可以作为小班因子调查的辅助手段,并可显著提高小班调查质量及效率。     

二氧化硅凝胶葡萄糖传感器上羟甲基纤维素酶活性测定

提出了用SiO2凝胶包埋葡萄糖氧化酶(GOD)电化学传感器(GOD/SiO2)测定羟甲基纤维素酶(CMCE)活性的方法,即基于电极对纤维素水解后生成葡萄糖的催化氧化.考察了各种实验条件对CMCE酶活性测定的影响.实验表明,GOD/SiO2电极检测电位为 0.57 V(以饱和甘汞电极为参比电极), 稳态响应电流与纤维素酶活性在5～400 U/L 之间有线性关系,该方法可用于微量羟甲基酶活性测定.