Design principles for origin-destination flow maps

Origin-destination flow maps are often difficult to read due to overlapping flows. Cartographers have developed design principles in manual cartography for origin-destination flow maps to reduce overlaps and increase readability. These design principles are identified and documented using a quantitative content analysis of 97 geographic origin-destination flow maps without branching or merging flows. The effectiveness of selected design principles is verified in a user study with 215 participants. Findings show that (a) curved flows are more effective than straight flows, (b) arrows indicate direction more effectively than tapered line widths, and (c) flows between nodes are more effective than flows between areas. These findings, combined with results from user studies in graph drawing, conclude that effective and efficient origin-destination flow maps should be designed according to the following design principles: overlaps between flows are minimized; symmetric flows are preferred to asymmetric flows; longer flows are curved more than shorter or peripheral flows; acute angles between crossing flows are avoided; sharp bends in flow lines are avoided; flows do not pass under unconnected nodes; flows are radially distributed around nodes; flow direction is indicated with arrowheads; and flow width is scaled with represented quantity.     

蚀变矿物填图技术在斑岩型铜矿找矿勘查中的应用—以滇西北香格里拉松诺矿床为例

松诺铜矿区位于香格里拉格咱斑岩铜矿带红山-普朗铜多金属成矿亚带中段,矿区剥蚀程度较低,具有寻找斑岩型铜矿的潜力。本次蚀变矿物填图工作采用近红外光谱矿物分析技术,识别出绿泥石、绿帘石、高岭石、云母类、蒙脱石类及伊利石等6类主要蚀变矿物,蚀变类型为青磐岩化、绢英岩化;结合物探、化探异常分布,圈定3处找矿靶区,经对KHT2、KHT3钻孔验证,深部均圈定多层铜矿化体。结果表明,近红外光谱矿物分析技术在斑岩型铜多金属矿床勘查评价中可以较好地划分热液矿化蚀变带,进一步明确斑岩型矿化-蚀变中心,为探矿工程部署提供依据。     

ASTER mapping of gypsum deposits of Thumrait region of southern Oman

This study demonstrates the use of ASTER data for the mapping of gypsum deposits and associated geological formations that occurred in the Thumrait region of southern Oman. The measurement of spectra over samples of gypsum in the 1,300–2,500 nm wavelength using a PIMA spectrometer showed the presence of distinct absorptions at 1400–1600, 1750, 1940, 2,100, and 2,400 nm characteristics to O? H stretching, H₂O combinations, and S? O bending overtones and stretching, respectively. Studying the unique spectral absorption characters of gypsum samples, we developed a false color composite (FCC) and an image by decorrelation stretch using the spectral bands 7, 3, and 2 of ASTER. The results FCC showed the regions of gypsum occurrences, and the decorrelated image discriminated the gypsum occurrences from other geological formations of the area. The study of surface mineralogy of the region using the VNIR‐SWIR bands by the spectral angle mapper method showed the presence of sulfate, carbonate, and clay minerals of the geological formations in the study area. We compared the results of ASTER with the results obtained using spectral bands 12, 8, and 4 of Sentinel‐2A processed by the same methods. The study showed that the spectral bands of ASTER can be used for mapping the gypsum and associated geological formations.     

黑龙江省浅覆盖区地物化特征与找矿标志——以黑河市340高地金矿化区为例

黑龙江省黑河市340高地金矿点大地构造上位于兴安地块东北缘,多宝山Cu-Au-Mo-W-Fe成矿亚带内,其地貌为浅覆盖区,找矿较为困难。本文采用浅钻技术取样,对研究区进行基岩填图,圈定出以硅化为中心、青磐岩化为外围的蚀变矿化带。对基岩样品进行岩石地球化学分析,通过主成分分析,确定有6个主成分特征值大于1,其中第二主成分与金元素关系密切,是研究区有效的找矿标志。高精度磁测结果显示区内构造以NNW向为主,且其线性低值异常或与蚀变引起的退磁有关。对区内的地物化异常进行工程查证,发现金矿点1处,圈定预测靶区1处。     

无人机遥感技术在甘肃北山地区地质填图中的应用

甘肃北山地区岩浆岩及变质岩出露广泛,植被稀少,地势平缓,是无人机遥感开展地质填图试验的理想目标区。为解决传统地质填图方法受地形、环境限制和投入高及工作周期长等问题,选取北山长流水地区20 km²化探重点工作区为目标区,利用大疆精灵4专业版无人机采集图像,并采用Photoscan软件合成高分辨率正射影像以及三维模型,建立解译标志,对目标区域进行地质解译,获得比前人1：1万地质图更加精细的地质图。该方法较传统填图方法能够解译出地质体形态、岩脉产状、微小断裂等更详细的地质内容,并能提供划分岩脉期次的证据。     

基于时序遥感的庐山自然保护区植被分类及其变化分析

自然保护区是生物多样性最丰富的区域,针对近年来庐山自然保护区森林生物多样性进行调查,了解保护区内植被的分布及其变化,对于保护庐山境内的林业资源具有重要的意义.论文利用2015-2018年Proba-Ⅴ卫星100m分辨率5d植被指数产品,使用最大值合成法、Hants时间序列谐波分析方法对数据进行平滑降噪处理,并采用随机森...     

基于PPGIS的乡村旅游社区景观价值变化研究——以丽江束河古镇为例

景观价值是人对环境的主观感知和效用评价,景观价值变化的研究能够帮助理解旅游社区的社会现象.以丽江束河古镇为例,采用参与式制图与半结构化访谈方法调查当地居民对旅游开发前后的感知景观价值,最终获取的有效问卷与填图为293份,提取空间数据点658个.通过对访谈结果进行编码和归纳得到旅游开发前后各7种景观价值类型.采用质性分析...     

浅谈测绘监理在第三次国土调查中的运用 ——以益阳市第三次国土调查监理为例

从1988年建设部颁布《关于开展建设监理工作的通知》算起,在我国工程建设领域推行工程监理制度已有三十多年历史.工程监理在工程建设过程中发挥了重要作用,我国目前在工程领域建立了完善的监理法规及标准体系,形成了较为完整的工程监理机制.但在测绘领域,全面推行测绘监理仍尚需时日,有待健全.湖南省各市州第三次国土调查项目引入了监...     

Vision-based tracking with projective mapping for parameter identification of remotely operated vehicles

Parameter identification of a remotely operated vehicle (ROV) is often based on the dynamic responses collected by its onboard sensors. However, for commercial ROVs, the required data for identification may not be available due to the absence of suitable sensors or limitations in accessing onboard sensor data. Therefore, this study proposes a vision-based tracking system to measure the dynamic response of an ROV. The tracking system is independent of the ROV, and is able to localize an ROV to a high degree of precision by means of projective mapping. The validity of the proposed tracking system is demonstrated through identification of a commercial ROV. A simplified nonlinear ROV dynamic model with six degrees of freedom (DOF) is used for identification. Uncoupled motions, including surge, sway, and yaw, are obtained from the ROV dynamic model, and the corresponding experiments are carried out for each DOF. Hydrodynamic parameters are then estimated with numerical optimizations by comparing the measured ROV responses with the output of the mathematical model. The experimental results show that the vision-based tracking system can accurately measure the transient and steady-state responses of an ROV. Additionally, the simulations of the ROV dynamic model, with the optimal parameter estimates, give results in agreement with the measured data.     

Coastal and estuarine habitat mapping, using LIDAR height and intensity and multi-spectral imagery

The airborne laser scanning LIDAR (LIght Detection And Ranging) provides high-resolution Digital Terrain Models (DTM) that have been applied recently to the characterization, quantification and monitoring of coastal environments. This study assesses the contribution of LIDAR altimetry and intensity data, topographically-derived features (slope and aspect), and multi-spectral imagery (three visible and a near-infrared band), to map coastal habitats in the Bidasoa estuary and its adjacent coastal area (Basque Country, northern Spain). The performance of high-resolution data sources was individually and jointly tested, with the maximum likelihood algorithm classifier in a rocky shore and a wetland zone; thus, including some of the most extended Cantabrian Sea littoral habitats, within the Bay of Biscay. The results show that reliability of coastal habitat classification was more enhanced with LIDAR-based DTM, compared with the other data sources: slope, aspect, intensity or near-infrared band. The addition of the DTM, to the three visible bands, produced gains of between 10% and 27% in the agreement measures, between the mapped and validation data (i.e. mean producer's and user's accuracy) for the two test sites. Raw LIDAR intensity images are only of limited value here, since they appeared heterogeneous and speckled. However, the enhanced Lee smoothing filter, applied to the LIDAR intensity, improved the overall accuracy measurements of the habitat classification, especially in the wetland zone; here, there were gains up to 7.9% in mean producer's and 11.6% in mean user's accuracy. This suggests that LIDAR can be useful for habitat mapping, when few data sources are available. The synergy between the LIDAR data, with multi-spectral bands, produced high accurate classifications (mean producer's accuracy: 92% for the 16 rocky habitats and 88% for the 11 wetland habitats). Fusion of the data enabled discrimination of intertidal communities, such as Corallina elongata, barnacles (Chthamalus spp.), and stands of Spartina alterniflora and Phragmites australis, which presented misclassification when conventional visible bands were used alone. All of these results were corroborated by the kappa coefficient of agreement. The high classification accuracy found here, selecting data sources, highlights the value of integrating LIDAR data with multi-spectral imagery for habitat mapping in the intertidal complex fringe.