How to calculate an average z-value for a ground surface

You can use a PointCloudStatisticsCalculator for that.

But for this I calculate the average z value for the hole pointcloud?

I will calculate average z-value for the drapedfeatures (ground surface of a building) after using surface drapper.

I have an idea. Maybe I can use AttributeCreator and add z-value by using fme feature functios (@ZValue()). After that I could calculate the average with the statistic calculator. But the feature function (@ZValue()) return only one z-value but I need all to calculate the average...

Just clip the pointcloud by the building footprint and use inside in PointCloudStatisticsCalculator 

Ok than I would calculate the z-mean for all points inside the groundpolygon. Is it possible to calculate the z-mean limited on the ground vertices?

Hello @limo​, just a thought (not tested), it may be easier to convert the ground surface to a point cloud using the PointCloudCombiner, and then try using a PointCloudStatsCalculator to get average? Best, Kailin

Yes this works for me. But I think I do not have to convert the ground surface to a point cloud. Because after clipping point cloud by ground polygon the result is already the ground as pointcloud. So this works for me fine. Thanks @caracadrian​  and @kailinatsafe​ 

I was just thinking only to calculate the average of the vertices of the ground polygon.