See this developer’s guide’s section on Picking for more information. Picking is also provided by the WorldWindow. Its associated navigator translates user input to movements of the globe. Behind the scenes, the WorldWindow retrieves imagery and elevation from the internet as needed, generates 3D terrain, and traverses the layer list to display its contents. Apps need do nothing but add layers and perhaps shapes and initiate redraws when it does so. The WorldWindow manages the display of the virtual globe or 2D map. The first thing most apps do is populate it with one or more imagery layers. The layer list holds all layers displayed in that WorldWindow, but it is initially empty. The globe and navigator may subsequently be replaced by the app if desired. These are all created automatically during construction of the WorldWindow object. Each encapsulates a separate canvas and operates independently of the others.Ī WorldWindow contains a Globe, a Navigator and a Layer List. Here the canvas is given an initial width and height of 1000 pixels, but the style element causes it to resize to the width of the containing when displayed, and maintain the initial aspect ratio.Ī web page may contain multiple WorldWindows. The canvas, itself, is defined in the associated HTML page as follows: Here’s an example of creating a WorldWindow for a canvas whose ID is “canvasOne”: var wwd = new WorldWind.WorldWindow("canvasOne") The WorldWindow directs all drawing to that canvas. The canvas is given an ID and that ID is handed to the WorldWindow constructor to tell the WorldWindow its drawing surface. The app developer is responsible for creating the canvas, typically by defining a element in static HTML. Almost all interactions between the app and Web WorldWind occur through a WorldWindow.Ī WorldWindow encapsulates an HTML canvas element. It represents the presence of Web WorldWind in the web page. Environmental Monitoring and Assessment 191:46įehrmann, L., Kukunda, C.B., Nölke, N., Schnell, S., Seidel, D., Magnussen, S., Kleinn, C.WorldWindow is the fundamental Web WorldWind object. A unified framework for land cover monitoring based on a discrete global sampling grid (GSG). Proceedings of the 5th international DAAD workshop, Durban and Pietermaritzburg, South Africa, 06.-, P. In: Bridging the gap between information needs and forest inventory capacity. A unified framework for environmental monitoring based on a discrete global sampling grid (GSG) system. Finally we conclude that the presented GSG is an easy to communicate and useful grid system for environmental monitoring. The required time consumption per plot (and the technical complexity that is required for such digitizing options) is simply too high and makes such digitizing exercises very inefficient compared to point clusters. About the configuration of observation units, we found that clusters of points are much more efficient for on screen data collection than digitizing land cover in fixed area plots. For some cases the data collection was straightforward and results were promising, however, a larger study on global forest cover was not successful because of remaining limitations in regard to image resolution over large forest areas around the world. It turned out that the Openforis Collect Earth toolbox is a very useful interface for the collection of data, while the generation of grids and observation units is done with the application developed in this project. In context of multiple case studies we collected data on land cover and land use in a project area in Indonesia (Sumatra), Eritrea, India and Germany. Further, we developed an R package and Shiny Server interface that allows generating sampling grids based on a discrete global grid system (GSG) and observation units based on point clusters of different extent and spatial configuration. We generated different observation designs for visual interpretations of high resolution remote sensing imagery and compared their performance against each other. In this project we tested the suitability of a global sampling grid for the assessment of land cover and land use. At the same time the increasing availability of large archives of freely available high resolution and geo-referenced imagery through virtual globes like Google Earth, Microsoft Virtual Earth (bing) or NASA World Wind and others is still relatively underexploited by scientific applications in this global environmental monitoring context. Erstellungsjahr 2019 Zusammenfassung der ProjektergebnisseĮnvironmental monitoring has been emerging as key factor in many international and national processes related to ecological and environmental challenges.
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