Cut Contours

Michael Tangwari 8 years ago in General updated by ronald reid 8 years ago 7
I am trying to cut a small region of a lidar contour string because the lidar covers a huge area and when I try to create a DTM Surface it takes forever to create and freeze up my laptop.

Hi Michael,

The easiest way is to filter it. You should be able to simply apply a filter with North greater than 888888 AND North less than 9999999 AND East greater than 88888 AND East Less than 99999 which will filter the strings to a small area. Eg

Make sure the filter covers the area you want and then right click on the name and select Edit -

when the file opens up select File -> Save As and the file will be saved as the filtered subset that you can use to create the DTM.

Hope this Helps


did u try "clip strings" button?

That works but requires more memory to process - Michael mentioned memory issues and this is one way I know of that requires less memory to get an end result. Although clipping is cleaner.
Thanks Guys I really appreciate your help.

I did try both options and Ron you are right the Clipping took up much memory and PC frozed.

I take both suggestions and will use depending on which PC I use.

Much appreciated, I managed to cut my strings.

I would first run Modelling>Implicit Modelling>Down Sample Points, if you have that function and if your Lidar data originated as points as it normally does.
Then limit the creation of the contour lines to a bounding box.
I am trying to wireframe a fault structure intersected in 3 adjacent holes and exposed on the surface in creeks.....how do I do that??

You assistance is greatly appreciated.

Mike - do you have the implicit modelling module? If so and you have some dip and dip direction readings it is a very easy procedure to use the fault modelling option with DH points as the input file (needs a minimum of 3 but you need Dip and Dir info) and the surface points as extra control points (2 will work). If you don't have Dip and Dip Dir for the DH intersections you need a minimum of 3 surface points with the DIp and Dip direction (even if one is just a "guestimate location" properly noted as such of course) and you can then use the DH points as the extra control points (leaving the DIp and DIp Dir fields empty). Else you could combine them into a single file and use the DTM -> create surface with a projection plane defined by the points or normal to the dip of the fault - you will have to add a few extra points to extend the surface though. Perhaps someone else knows of a better way but for ease of use and best output the IM-Fault modelling option is a good step.