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When point cloud data is collected,将各种组件分配给每个单独的点,包括坐标,强度,and classification.在创建曲面模型时,使用点分类可以快速轻松地识别地面点,以便从中提取曲面模型。In the examples below we will demonstrate how a custom transformer called thePointCloudLASClassifiercreated by a 亚搏在线Safe Software team member can be used within a 亚搏在线workflow to create a DEM or TIN model.
The custom transformer PointCloudLASClassifier can be used to increase the accuracy of a DEM or TIN output by extracting just the ground points.If the point cloud data that you are working with does not have a classification component,然后使用shapefiles删除非接地点,像建筑物一样,可以使用。Thisarticle解释如何做到这一点。
要沿点云边缘生成正确的高程,必须考虑所有相邻点云瓷砖。然而,generating a single digital elevation model (DEM) for the center tile and all adjacent tiles can significantly affect performance.为了减少整体数据量,我们可以围绕中心点云块生成一个相对较小的缓冲区,并用该缓冲区裁剪相邻块的边缘。生成的点云(中心瓷砖和相邻瓷砖的边缘)将用于制作DEM光栅,然后可以将光栅剪裁到中心平铺的原始范围。
a.B.
Image a.shows the original point cloud data with the central tile of interest selected.Image b.是从下面的las到dem工作流生成的dem输出。亚搏在线
DEM是代表地球表面的常用模型。They are raster based models with cell values representing different levels of elevation.由于每个单元是表面积高程的平均表示,natural landscapes appear smooth,而人造景观显得粗糙。使用FME从LAS数据创建DEM快速简单,因为您只能使用地面分类点来创建模型。
点云中的点有一个称为分类的组件。组件中的代码值表示类建筑物或地面。为了创建DEM,我们只需要地面类。The steps for creating a DEM from a point cloud are as follows:
Optional: Try running the workspace without the link from the PointCloudLASClassifier transformer to the RasterDEMGenerator and instead connect the "Split" points from the PointCloudSplitter.Compare the different output DEMs.
a.B.
Image a.显示在工作流中使用所有点创建DEM时,DEM输出的外观。亚搏在线Image b.Is what the DEM looks like when only the ground classified points are used.Using only the ground classified points creates a much smoother and realistic representation of the ground itself.
如果使用其他LAS文件生成DEM,检查这些点是否带有分类。如果是这样,确保只使用适当的类来生成DEM。
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当点云具有分类组件时,可以获得用建筑物创建曲面模型的最佳结果。We can use the Data Inspector orPointCloudPropertyExtractor以检查此组件是否存在。如果点云的分类为2,地面,它通常足以生成表面。然而,排除建筑物仍然有助于建立更精确的模型,因为它有助于避免分类错误。Thisarticle解释有关按类拆分点云的更多信息。此工作区的步骤如下:
The output from this workspace is much smoother.Note that the bridges have disappeared from the model.这意味着它们有一些其他的分类,而不是地面:
This workspace generates a TIN (as a 3D PDF file) using a DEM as a texture:
你好,米塔
I triedlas_to_textured_tin_fme2011.fmwtand it gave me blank PDF after 14 minutes running.我这里缺什么?你能提出建议吗?
@海卡尔It's hard to say without looking at your data/workspace.请注意,工作区正在读取图块,然后在工作区中对它们进行一些处理。你也在看瓷砖吗?Does the log report any errors/warnings?We have a debugging guide that should helphttps://knowledge.亚搏在线safe.com/articles/19301/root-cause-analysis-guide.html网站
你好
我尝试了你的las to dem,我得到了“翻译成功,有1个警告(0个功能输出)
FME会话持续时间:24分钟52.7秒。(CPU:1489.6S用户,1.1s system)
结束进程ID:5428,峰值进程内存使用率:1322008 KB,当前进程内存使用量:50552KB
Translation was SUCCESSFUL"
然而,我无法显示结果,有什么建议吗?
当做
Please find attached my *.fmw filemita-las-to-dem.fmw
I appreciate any advice and recommendation
Hi@海卡尔日志显示您有“0个功能输出”。There are transformers in your workspace that need to be connected,and also that don't have their properties set.我建议移除除RasterdemGenerator以外的所有东西,看看是否有效,至少。如果您仍然有问题,请将您的工作区和源数据发送给我们的支持团队。https://support.亚搏在线safe.com/knowledgeSubmitCase
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