SPAN8.
SPAN4.
本文也是教程的一部分我如何在FME中这样做|下一篇:识别分水岭
光栅斜坡可以以两种方式测量:斜坡角度和斜坡方面(方向)。在FME斜率角度用Rasterslopecalculator变压器和斜率方面测量,与栅格扫描器。
In this tutorial we will try each of these transformers to see what they do, and then use the RasterSlopeCalculator in a workspace that assesses land-use capabilities.
这些示例的源数据是CDED格式的栅格DEM数据集。在FME数据检查器中,它看起来像这样:
颜色打火,高度越高。较暗的区域代表低洼地区。
1.启动FME工作台并以空的画布开头。选择读者>从Menubar添加读者。
当提示地将数据格式设置为加拿大数字高程数据(CDED)(或U.S.地质调查数字高度模型(USGSDEM) - 这两个是相同格式的不同名称)。
Select the attached data as the source dataset.
2.放置帆布上的RastersLopecalculator变压器和一个栅格扫描器。从读取器功能类型绘制连接到每个变压器,然后将来自每个变压器的输出连接到检查器变压器:
检查每个栅格计算器的参数对话框,以查看可用的选项,但通常会使参数留下它们。
3.运行工作区。结果将是FME数据检测器中出现的两个栅格功能。
Turn off background maps, if you have them turned on, as they will make it harder to query the data.
现在依次隐藏每个栅格,使您能够检查另一个。
斜率特性如下所示:
Query some of the raster cells by clicking on them. Each cell now represents the slope at that location, rather than elevation. You will be able to pick out bright spots in the centre and right of the image. These are features that - although low-lying - have a steep slope.
The aspect feature looks like this:
每个单元格现在表示从0-360度的该位置处的斜率的方向。FME不会很好地可视化,因为它将值从零(非常暗)解释为360(非常亮起),但您可以通过单击它来识别每个单元格的值。
4.我们可以(可选)调整坡度方面a better display using the RasterExpressionEvaluator transformer.
Place a RasterExpressionEvaluator into the workspace between the RasterAspectCalculator and the Inspector it is connected to. Open the parameters dialog. Set interpretation to "Preserve". Double-click the Expression field and use the drop-down arrow to open the arithmetic calculator.
Inside the calculator enter the following expression:
if (A[0]>180,@abs(A[0]-360),A[0])
这将使方面顺时针和逆时针计算0到180。结果看起来像这样:
Notice how the coloring is now more consistent, making it easier to see the dark areas that face north.
1. This exercise is going to use raster data and the RasterSlopeCalculator to calculate the suitability of land for development. Building developments usually prefer land that is both flat and low-lying.
Start FME Workbench and begin with an empty canvas. Select Readers > Add Reader from the menubar.
当提示地将数据格式设置为加拿大数字高程数据(CDED)(或U.S.地质调查数字高度模型(USGSDEM))并选择附加数据作为源数据集。
2. Place a RasterSlopeCalculator transformer and draw a connection from the reader feature type to the transformer.
3.放置RasterCellvaluecalculator变压器。从读取器功能类型绘制第二个连接到RasterCellvaluecalculator:输入端口。从RastersLopecAlculator绘制连接:输出端口到RasterCellvalueCalculator:B输入端口:
4.打开RasterCellvaluecalculator的参数对话框。只需将操作参数更改为+选项;即,这将将原始数据(表示高程)添加到转换的数据(表示斜率)。结果将代表每个细胞建立开发的适用性:
The lighter colors represent cells that have both a steep slope and a higher elevation. Darker colors represent cells that have both a shallow slope and a low elevation.
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