QGIS comes with many built-in tools to calculate and summarize raster area.備註 Historically the suggested approach for calculating areas for rasters was to convert the raster to a vector layer and use vector area calculation techniques. This approach is quite computationally intensive and error-...
在使用QGIS加载了网上下载的中国GeoJSON数据,但计算面积的时候得到的数据是NULL,如下图所示 原因分析 在QGIS中,面积计算是通过面积计算器来实现的,面积计算器的原理是通过投影坐标系来计算的,如果投影坐标系不正确,那么面积计算器就会出现问题。 一般这种情况下你可能忘记将空间数据进行投影,投影方法可以参考这篇文章:...
Checked in 2.8.1 and it's still providing incorrect area back when OTF ProjectingContributor Author qgib commented Apr 19, 2015 Author Name: Andre Joost (Andre Joost) Just another test case: http://gis.stackexchange.com/questions/143080/qgis-area-calculation-differs-when-on-the-fly-crs-trans...
>I am wondering if the method for area/distance calculation has changed again >in master or if the issue is in some transformation accuracy changes. > >In QGIS docs, we are getting failing tests for calculation we did not touch >the underlying data for years. >See starting from >https:/...
开发者ID:AnAvidDeveloper,项目名称:QGIS,代码行数:30,代码来源:globe_plugin.cpp 示例3: mapWidth ▲点赞 4▼ doubleQgsComposerScaleBar::mapWidth()const{if( !mComposerMap ) {return0.0; } QgsRectangle composerMapRect = mComposerMap->extent();if( mUnits == MapUnits ) ...
# 需要导入模块: from qgis.core import QgsDistanceArea [as 别名]# 或者: from qgis.core.QgsDistanceArea importareaUnits[as 别名]classSizeCalculator():"""Special object to handle size calculation with an output unit."""def__init__(
Is the area calculation method different? If they are different and QGIS method is actually more accurate, does it sacrifice speed to get it? If they are the same, is there a difference in the precision of the calculations? I did a little digging on the turf side: ...
Preprocessing of satellite scenes and calculation of the NDVI The normalised difference vegetation index (NDVI) is used as one of the various remote sensing methods. It is widely applied to monitoring vegetation condition and assessing the impact of climate on vegetation dynamics. The NDVI was first...
configureDistanceArea( myDa );//angle calculationdoubleazimuthOne = myDa.bearing( mAnglePoints.at(1), mAnglePoints.at(0) );doubleazimuthTwo = myDa.bearing( mAnglePoints.at(1), point );doubleresultAngle = azimuthTwo - azimuthOne; QgsDebugMsg( QString::number( qAbs( resultAngle ) ) ); ...
开发者ID:grizonnetm,项目名称:QGIS,代码行数:21,代码来源:test_qgsdistancearea.py 示例2: testMeasurePolygonWithHole ▲点赞 6▼ # 需要导入模块: from qgis.core import QgsDistanceArea [as 别名]# 或者: from qgis.core.QgsDistanceArea importmeasureArea[as 别名]deftestMeasurePolygonWithHole(self):#...