The scale and precision of Bing Maps

If you wanna download the Bing maps or Bing satellite, how do you finish this task? As you know that you cannot directly download it to your hard disk. All you need is just a Bing Maps downloader to help you finish this task. But not all the Bing Maps downloader can download the accurate maps, in order to download the high definition maps and without any deviation. You can try Maps downloader for Bing satellite or Maps downloader for Bing Map.

Now let’s go down to our business.This article we are going to talk about the scale and precision of Bing Maps.We all know that the earth is round, and every day we see the electronic map including paper maps are flat . For the sake of convenience, we have to sacrifice the accuracy , mapping the irregular sphere into a plane , this is what we see the most commonly used Mercator map (Mercator Projection)now, including Bing Maps that almost all electronic maps are used Mercator projection. The benefits of using the Mercator projection is that suppose we sail in the sea , we go straight in accordance with the instructions compass straight, on a plane corresponding map is a straight line, although in fact go on the sphere is a space curve.

Of course Mercator Projection there will be some problems because it is adopted parallel warp and weft , which means that the distance corresponds to a time warp or the weft are equal . But on Earth body , the distance between the equator and the poles was clearly unequal . The benefits of using Mercator Projection is that it makes it easier for us to draw and understand maps.

How to calculate the resolutionThe resolution of the map is an equation composed of latitude, zoom level, and the constant. At any latitude and level of zoom, the accuracy of map accuracy can be expressed by the following equation:Map resolution = 156543.04 meters / pixel * cos (latitude) / (2 ^ zoomlevel)Here the zoomlevel value is an integer between 1-19 , latitude is -90 to +90 . The closer the distance, the greater the error in this equation . This is the problem of Mercator Projection . From this

equation , we probably can calculate for each level of magnification and each pixel on the screen represents the distance ratio.(on equator).

It should be noted that, at different latitudes the ratio on the map will change. For example, in Toronto Canada (Toronto, dimensions 43.65 ) , map zoom level is 13 , map accuracy is about 19.11 * cos (43.65) or 13.8 meters / pixel.

How to calculate the scale of map?Most of the time, we are more concerned about the scale of the map because we are accustomed to a fixed percentage of map, for example 1 : 5000 , one centimeter on map corresponds to 50 meters on Earth. In order to calculate the scale, you need to know the screen resolution , the map zoom level , and dimension values . Furthermore, we assume that the resolution of the screen is fixed, the direction of the x and y coordinates are equal . Scale computing equation is as follows:Map scale = 1 : (ScreenRes pixels/inch * 39.37 inches/meter * 156543.04 meters/pixel * cos(latitude) / (2 ^ zoomlevel))

For example , assume that the screen resolution is 85 / inch , map zoom level is 13 , you can get a scale 1: 85 * 39.37 * 19.11 or 1: 63 950 .Most of the time we do not need to calculate the scale or map accuracy , because this is usually done by Microsoft Bing Maps. But when you do some application develop you may need to consider these factors , such as car navigation or calculating the distance .

Bing maps and SilverLightTraditional online map almost invariably is adopted the JavaScript form controls. We must admit that innovation really brought a lot

convenience to the development. It makes developers do not need to have the GIS background knowledge they can develop some simple LBS applications. When Microsoft gives the online interactive SDK , the program development becomes more simple, only need to copy , paste, replace some of the parameters .Microsoft launched Bing Maps SilverLight control (Bing Maps SL Control) with SilverLight technology continues evolving and developers become more familiar with SilverLight , SilverLight -based map applications are increasingly widespread.

IDV Solutions，DOD Collaborative GIS

IDV Solutions is a Microsoft Gold Partner which provide many solutions for developing Bing Maps. The figure above shows one of the IDV items DOD Collaborative GIS, Department of Defense collaborative GIS platform. When the occurrence of unexpected events ( terrorist hostage-taking , house on fire , accidents , etc. ) , the relevant departments could work together online , conduct research on the Bing Maps , simulated accident scene ,simulate offensive line , etc. . Bing Maps provides high-resolution satellite images of the scene of the incident and clearly show the geographical situation , and SilverLight page provides a good interaction . Users can easily drag a variety of objects to the map, such as airplanes , trucks , people, buildings , etc.

For more information about Bing Maps Downloader you can visit: www.arceyessoft.com