COMPACT AIR FILM PROCESSORS AND THEIR APPLICATIONS

The essential features of equipment for mobile processing are outlined with reference to the development of small photographic laboratory vehicles for use in the Jield. The resulting air film processor, the Wainco Products Limited 392. is described and details are given of trials carried out to establish its performance for a range of tasks in both reconnaissance and survey. The tests cover the sensitometric and drying behaviour of several air films in current use and include an analysis of the dimensional stability o f j l m in the processor. Applications using direrent containers and eflectiveness in improvised situations are also described and possible future variants of the processor are suggested.     

Forest type mapping and volume stratification of man-made forests with aerial photographs

The use of panchromatic (black & white) aerial photographs on 1:15,000 scale for forest type mapping and evolving a suitable basis of volume stratification for man-made forests of Haldwani Division of U.P. is discussed. Forest types by species, height and density were identified and ground survey data collected in 0.1 hectare circular plots were used to evolve the basis of volume stratification by statistical analysis. The methodology used for pilot studies before regional surveys are undertaken is presented.     

Aerial Photographs and Forest Maps in India

A comparative case study of forest cover type mapping from 1:10,000 scale black and white panchromatic aerial photographs and by conventional ground methods of Gudem Reserve Forest of Kaghaznagar Forest Division of Andhra Pradesh Forest Department has been made. The study highlights the advantages of mapping from aerial photographs. The study indicates about the cost and time required for forest cover type mapping by aerial photo-interpretation techniques which is about half, and nearly one fourth respectively, of that required by ground methods.     

RECOLLECTIONS OF A SURVEY OFFICER IN INDIA

Abstract

Crabs! Thousands of bright red crabs on a white foreshore; clinging black mud in tidal creeks with an overhanging tangle of tropical forest. These dominate one's memories of the Irrawaddy Delta in 1924. The Forest Department of Burma is the custodian of some 1,000 square miles of valuable forest reserves in the delta of this great river. The survey and production of “Forest” maps of this area was long overdue, postponed by reason of the immense expense and difficulty of a ground survey. Air survey, developed during the First World War, was ideally suited to this type of country but was still in its infancy, so that prolonged negotiations were necessary to persuade the Government of Burma to risk £25,000 on what appeared to them a doubtful proposition, as this was one of the first of the peace-time air surveys to be undertaken. Eventually, in July 1923 the contract was signed. Ronald Kemp, the first Chief Inspector of Civil Aircraft in India, gave up that post and formed an air survey company to carry out the photography as the first of his many survey contracts in India and Burma; I was in charge of the ground work and subsequent mapping.     

机载激光雷达平均树高提取研究

为了研究机载激光雷达(LiDAR)树高提取技术,以山东省泰安市徂徕山林场为实验区,于2005年5月进行了机载LiDAR数据获取和外业测量.通过对LiDAR点云数据的分类处理,分别得到了试验区的地面点云子集、植被点云子集和高程归一化的植被点云子集.基于高程归一化的植被点云子集计算了上四分位数处的高度,与实地测量的数据进行了比较,并结合中国森林调查规程进行了实用性分析.结果表明:对于较低密度的点云数据,使用分位数法可以较好地进行林分平均高的估计;机载激光雷达技术对树高估计是可行的,精度都高于87%,总体平均精度为90.59%,其中阔叶树的精度高于针叶树.该试验精度可以满足中国二类森林调查规程中平均树高因子的一般商品林和生态公益林的精度要求,对国有商品林小班的调查精度要求(5%)存在一点差距,需要在国有商品林区进一步开展验证工作.对本试验区而言,已经可以满足其作为森林公园生态公益林的调查要求.     

An automated object-based approach for the multiscale image segmentation of forest scenes

Over the last decade the analysis of Earth observation data has evolved from what were predominantly per-pixel multispectral-based approaches, to the development and application of multiscale object-based methods. To empower users with these emerging object-based approaches, methods need to be intuitive, easy to use, require little user intervention, and provide results closely matching those generated by human interpreters. In an attempt to facilitate this, we present multiscale object-specific segmentation (MOSS) as an integrative object-based approach for automatically delineating image-objects (i.e., segments) at multiple scales from a high-spatial resolution remotely sensed forest scene. We further illustrate that these segments cognitively correspond to individual tree crowns, ranging up to forest stands, and describe how such a tool may be used in computer-assisted forest inventory mapping. MOSS is composed of three primary components: object-specific analysis (OSA), object-specific upscaling (OSU), and a new segmentation algorithm referred to as size constrained region merging (SCRM). The rationale for integrating these methods is that the first two provide the third with object-size parameters that otherwise would need to be specified by a user. Analysis is performed on an IKONOS-2 panchromatic image that represents a highly fragmented forested landscape in the Sooke Watershed on southern Vancouver Island, BC, Canada.     

基于CHRIS数据的HDVI植被指数的植被覆盖度估算研究

选取江西省余干县的一景CHRIS/PROBA影像5个观测角度(±55°、0°和±36°)的反射率,在CHRIS数据处理后得到的NDVI基础上得到HDVI,并与野外实测的草地、灌木、针叶林、针阔林和阔叶林的VFC建立相关性分析,以及对于模型拟合度的决定系数R2的影响因素进行分析。结果表明,在±55°下,针阔林的多项式拟合度最高,植被类型模型的拟合度均值也最高。其次是灌木拟合度较高。最差的是针叶林指数模型,植被类型的整体拟合度最不理想。在±36°下,针阔林多项式拟合度最高,植被类型的整体拟合度也最高,其次是阔叶林拟合度较高。最差的是针叶林的指数模型,植被类型的整体拟合度也是最不理想的。     

决策树结合混合像元分解的中国竹林遥感信息提取

竹林是中国亚热带地区特殊而重要的森林资源,现有方法难以实现全国范围竹林时空分布信息快速准确提取。针对此问题,本研究利用2003年、2008年、2014年MODIS NDVI、反射率产品数据和省域Landsat分类数据,提出了基于决策树结合混合像元分解的全国竹林信息提取方法。首先,通过最大似然法获取中国林地分布信息;然后,在林地信息的基础上,构建决策树模型提取中国竹林分布信息;最后,采用线性最小二乘法混合像元分解得到中国竹林丰度图,并计算竹林面积。研究结果表明:(1)最大似然法提取的3个时期中国林地信息的生产者与用户精度均在90%以上,Kappa系数均值为0.93,为竹林信息提取奠定了基础。(2)C5.0算法构建的决策树模型能够很好的提取中国竹林时空分布信息,3个时期竹林分类精度均在80%左右。(3)在混合像元分解的基础上,统计得到的全国各省竹林估算面积与清查面积具有较高的相关性,R~2分别为0.98、0.97和0.95,RMSE范围为3.92万—9.58万ha,说明估算得到全国竹林面积与实际情况较为吻合。本研究所提出基于MODIS遥感数据运用C5.0算法决策树结合混合像元分解的方法,实现了全国竹林时空分布信息的准确提取,为全国竹林资源信息动态监测及管理提供了技术手段和数据支撑。     

SOME ASPECTS OF PHOTOGRAPHY IN AIRBORNE SENSING

The paper discusses aspects of air photography and electronic processes which produce imagery by infra-red radiation and by radar waves. After preliminary comments on lenses, laboratory techniques and colour photography, the author indicates certain advantages in simultaneous photography using black and white, infra-red and colour films. Moreover, information is given on simultaneous photography by satellite and the paper terminates with a resume of methods that are used to obtain imagery by infra-red radiation and by radar.     

Estimates of forest structure parameters from GLAS data and multi-angle imaging spectrometer data

Quantitative estimates of forest vertical and spatial distribution using remote sensing technology play an important role in better understanding forest ecosystem function, forest carbon storage and the global carbon cycle. Although most remote sensing systems can provide horizontal distribution of canopies, information concerning the vertical distribution of canopies cannot be detected. Fortunately, laser radars have become available, such as GLAS (Geoscience laser altimeter system). Because laser radar can penetrate foliage, it is superior to other remote sensing technologies for detecting vertical forest structure and has higher accuracy. GLAS waveform data were used in this study to retrieve average tree height and biomass in a GLAS footprint area in Heilongjiang Province. However, GLAS data are not spatially continuous. To fill the gaps, MISR (multi- angle imaging spectrometer) spectral radiance was chosen to predict the regional continuous tree height by developing a multivariate linear regression model. We compared tree height estimated by the regression model and GLAS data. The results confirmed that estimates of tree height and biomass based on GLAS data are considerably more accurate than estimates based on traditional methods. The accuracy is approximately 90%. MISR can be used to estimate tree height in continuous areas with a robust regression model. The R², precision and root mean square error of the regression model were 0.8, 83% and 1 m, respectively. This study provides an important reference for mapping forest vertical parameters.     

Effect of flying altitude and pulse repetition frequency on laser scanner penetration rate for digital elevation model generation in a tropical forest

In tropical forests, the penetration ability of airborne laser scanning (ALS) may be limited because of highly dense vegetation cover. However, in the typical planning of ALS surveys, the ability of laser pulses to penetrate forests is not considered. Nine round-trip flight lines covering the area of a tropical forest on the northeast side of the Tsengwen Reservoir in Taiwan were designed in this study. Five flight lines flew at altitudes of 1.525, 1.830, 2.135, 2.440, and 2.745 km, and the other four had pulse repetition frequencies (PRFs) of 100, 150, 200, and 250 kHz. The laser penetration index (LPI) is a quantitative index measuring the penetration ability of the ALS and consists of the ratio of the number of laser pulses reaching the forest floor to the total number of laser pulses. The LPI was used to represent the laser penetration rate and investigate the influence of flying altitude and PRF on the LPI. The results showed that as the flying altitude decreased by 1 km, the average LPI increased by 10%, and as the PRF decreased by 50 kHz, the average LPI increased by 2%. The effect of the LPI on digital elevation models (DEMs) was confirmed by visual images obtained by DEMs at five altitudes. The DEM obtained at an altitude of 2.745 km was coarsely textured, whereas that obtained at an altitude of 1.525 km was finely textured. The in-situ height data obtained from the electronic Global Navigation Satellite System (eGNSS) were compared with the data of the ALS-generated DEMs. The results indicated that when the LPI ≥60%, the height difference between the in situ data and DEM data was not prominent. However, when the LPI <60%, the ALS-derived DEM could be higher or lower than the in-situ height; the largest difference between the two was 1.7 m. The LPI of a forest should be considered for ALS survey planning, especially when consistent DEM precision for large tropical forest areas is paramount.     

A heuristic‐based approach to mitigating positional errors in patrol data for species distribution modeling

Species distribution modeling (SDM) at fine spatial resolutions requires species occurrence data of high positional accuracy to achieve good model performance. However, wildlife occurrences recorded by patrols in ranger‐based monitoring programs suffer from positional errors, because recorded locations represent the positions of the ranger and differ from the actual occurrence locations of wildlife (hereinafter referred to as positional errors in patrol data). This study presented an evaluation of the impact of such positional errors in patrol data on SDM and developed a heuristic‐based approach to mitigating the positional errors. The approach derives probable wildlife occurrence locations from ranger positions, utilizing heuristics based on species preferred habitat and the observer's field of view. The evaluations were conducted through a case study of SDM using patrol records of the black‐and‐white snub‐nosed monkey (Rhinopithecus bieti) in Yunnan, China. The performance of the approach was also compared against alternative sampling methods. The results showed that the positional errors in R. bieti patrol data had an adverse effect on SDM performance, and that the proposed approach can effectively mitigate the impact of the positional errors to greatly improve SDM performance.     

A NATURAL RESOURCE EVALUATION OF ERTS-1 IMAGERY OF THE CENTRAL AFAR REGION IN ETHIOPIA

System corrected multispectral imagery of the Central Afar region in Ethiopia provided by the ERTS-1 satellite was evaluated for the purposes of natural resource inventory under the headings of geology, vegetation, soils and land use. The methods and results of image interpretation are discussed in detail and the following general conclusions may be drawn. The ERTS-1 imagery provides a synoptic view of the region that is very nearly orthographic. A colour composite print of multispectral bands 4, 5 and 7 is superior to any of the individual black and white bands for natural resource interpretation. Exploratory soil, vegetation and land use maps and reconnaissance geological maps can be constructed rapidly. The small percentage of forest and agricultural land in this particular area enhances the geological value of the image. Satellite imagery is a valuable addition to the more conventional forms of aerial photography for agricultural studies provided that the study area covers at least 10 000 km². Ground control was acquired between October 1972 and May 1973.     

Forest classification and impact of BIOMASS resolution on forest area and aboveground biomass estimation

The European Space Agency (ESA) is currently implementing the BIOMASS mission as 7th Earth Explorer satellite. BIOMASS will provide for the first time global forest aboveground biomass estimates based on P-band synthetic aperture radar (SAR) imagery. This paper addresses an often overlooked element of the data processing chain required to ensure reliable and accurate forest biomass estimates: accurate identification of forest areas ahead of the inversion of radar data into forest biomass estimates.The use of the P-band data from BIOMASS itself for the classification into forest and non-forest land cover types is assessed in this paper. For airborne data in tropical, hemi-boreal and boreal forests we demonstrate that classification accuracies from 90 up to 97% can be achieved using radar backscatter and phase information. However, spaceborne data will have a lower resolution and higher noise level compared to airborne data and a higher probability of mixed pixels containing multiple land cover types. Therefore, airborne data was reduced to 50 m, 100 m and 200 m resolution. The analysis revealed that about 50–60% of the area within the resolution level must be covered by forest to classify a pixel with higher probability as forest compared to non-forest. This results in forest omission and commission leading to similar forest area estimation over all resolutions. However, the forest omission resulted in a biased underestimated biomass, which was not equaled by the forest commission. The results underline the necessity of a highly accurate pre-classification of SAR data for an accurate unbiased aboveground biomass estimation.     

Evaluation of Morphological Texture Features for Mangrove Forest Mapping and Species Discrimination Using Multispectral IKONOS Imagery

This letter aims to exploit morphological textures in discriminating three mangrove species and surrounding environment with multispectral IKONOS imagery in a study area on the Caribbean coast of Panama. Morphological texture features are utilized to distinguish red (Rhizophora mangle), white (Laguncularia racemosa), and black (Avicennia germinans) mangroves and rainforest regions. Meanwhile, two fusion methods are presented, i.e., vector stacking and support vector machine (SVM) output fusion, for integrating the hybrid spectral–textural features. For comparison purposes, the object-based analysis and the gray-level co-occurrence matrix (GLCM) textures are adopted. Results revealed that the morphological feature opening by reconstruction (OBR) followed by closing by reconstruction (CBR) and its dual operator CBR followed by OBR gave very promising accuracies for both mangrove discrimination (89.1% and 91.1%, respectively) and forest mapping (91.4% and 93.7%, respectively), compared with the object-based analysis (80.5% for mangrove discrimination and 82.9% for forest mapping) and the GLCM method (81.9% and 87.2%, respectively). With respect to the spectral–textural information fusion algorithms, experiments showed that the SVM output fusion could obtain an additional 2.0% accuracy improvement than the vector-stacking approach.      

森林航空摄影比例尺和森林判读像片放大倍数的研究

为了确定森林航空摄影的最佳比例尺和波段以及判读像片的放大倍数,我们在广东省南昆山林业遥感试验场,测定了地物光谱,拍摄了不同比例尺的多光谱片和彩色红外片,进行了内业判读、野外检测和综合分析。本文讨论了航空摄影机、胶片、地物光谱反射系数和摄影位移等因素对像片分辨力的影响,用经验关系式估算了南昆山像片的影像分辨力,阐述了内业判读和实地检测的情况。试验表明,在所试验的波长附围内绿波段表达森林影像的效果最佳,用于森林判读的影像分辨力宜放大到3.5线/毫米,若用新型航空摄影机和高分辨力胶片,则用于森林资源调查分类判读的像片比例尺可缩小到1:4.8万。     

Land use pattern of upper tons catchment district,Uttarkashi, U. P.

Aerial Photographs of 1:50,000 scale pertaining to Tons Catchment were used for generating a land use map showing cultivated lands, forests land, grass land, barren land with rock outcrops, snow and glaciers. The area was divided into 4 altitudinal Zones. More than 81% lies above 3000 m height and should be left for natural regeneration. Cultivated land occupies 4.97% of the area and is concentrated below 3000 m altitudinal zone and lies along river courses and on river terraces. Distribution of forest lands in altitudinal zone indicates that percent area covered under forest is higher than the average distribution of forest as reported by Seth (1978). Grass and open scrub, barren Innd with rock outcrops, glaciers and snow covered areas occupy 6.8%, 18.1%, 16.5% and 28.0% respectively.     

Spectral Characteristics of Weathered Oil Films on Water Surface and Selection of Potential Sensitive Bands in Hyper-Spectral Images

This study was an experiment to measure the reflectance data of water and oil films at the 0, 1st, 3rd, 12th, and 48th h of weathering and analyzed the spectral reflectance characteristics of the weathered oil films. Based on the experiment and analysis, the measured data were resampled through the spectral response function of the hyperspectral data. The environmental noise equivalent reflectance difference of the image data was then used to assess the sensitivity of each band for the detection of oil films. The bands that were most effective in detecting oil films in various stages of weathering were assessed. Results indicated that the spaceborne hyperspectral sensor employed in this study had the potential to discriminate among oil films in different stages of weathering. At the 0, 1st, 3rd, and 12th h of weathering, discrimination between water and oil films and among oil films in varying stages of weathering was achieved at the visible and near-infrared bands. After 48 h, the potential sensitive bands were distributed mainly in the near-infrared region. This experiment can provide a method to select bands of hyperspectral data for monitoring oil films.     

Forest site quality assessment by aerial photo-interpretation case study of sal forests

93 black & white panchromatic aerial photographs of 1972 on 1:20,000 scale were used for assessing the site quality of Sal forest of part of West Dehradun Forest Division, by both direct and indirect methods. The forests were stratified into 5 height and 5 density classes and according to species composition. For necessary data for the assessment of growing stock, field measurements were made on 54 sample plots of 0.1 hectare each. This provided direct indication of actual productive capacity of a particular site. According to indirect method, ground vegetation was sampled in 54 quadrats of 5m x 5m each and has been classified into statistically sound vegetation groupings by normal association analysis technique. These groups facilitated the standardisation of their photo perameters. The indicator value of the plants in a grouping was used to assess the suitability of the site. This was substantiated by super-imposing growing stock, present at that site. By combination of the direct and indirect methods, sites have been classified into 3 categories i.e., suitable, conditionally suitable and unsuitable. Suggestions have been made for management of conditionally suitable sites and the cause for unsuitability of sites are explored. Hence, interpretation of qualitative attributes of vegetation alongwith the measurements of quantitative parameters on aerial photographs have proved to be useful for site quality assessment.