topic Re: Creating TIN with soft clip does not reach full extent of polygon in 3D Questions

Creating TIN with soft clip does not reach full extent of polygon

Waan — Thu, 31 Oct 2013 16:07:34 GMT

I've got a question concerning soft clips during the TIN creation process.

Like a number of posters here, I'm trying to model subsurface geology using boreholes--though I'm also combining surface outcrops as well (in the form of high-density elevation points overlaid with geology).

I've noticed a number of my TINs do not fully "fill out" the soft clip polygons I use for them. They may reach only part of the polygon edge and not the full extent.

Attached is a screen shot illustrating one of these. The only input here were some high-res mass points over the outcropping unit (in the screenshot, they mimic the underlying lidar-derived DEM) and a soft clip polygon boundary (shown in dark red). However, as can been seen toward the bottom of the image, the TIN creation process only fills in part of the polygon. The polygon is very simple and quite small, but there seems to be some (non-explicit?) threshold beyond which the TIN creation process will not extend to a soft clip boundary. Does this have to do with edge length, point spacing, or something else entirely?

If anyone can shed some light on this, I'd appreciate it.

Thanks,
Warren

Re: Creating TIN with soft clip does not reach full extent of polygon

TimBarnes — Wed, 13 Nov 2013 00:03:15 GMT

I've got a question concerning soft clips during the TIN creation process.

Like a number of posters here, I'm trying to model subsurface geology using boreholes--though I'm also combining surface outcrops as well (in the form of high-density elevation points overlaid with geology).

I've noticed a number of my TINs do not fully "fill out" the soft clip polygons I use for them. They may reach only part of the polygon edge and not the full extent.

Attached is a screen shot illustrating one of these. The only input here were some high-res mass points over the outcropping unit (in the screenshot, they mimic the underlying lidar-derived DEM) and a soft clip polygon boundary (shown in dark red). However, as can been seen toward the bottom of the image, the TIN creation process only fills in part of the polygon. The polygon is very simple and quite small, but there seems to be some (non-explicit?) threshold beyond which the TIN creation process will not extend to a soft clip boundary. Does this have to do with edge length, point spacing, or something else entirely?

If anyone can shed some light on this, I'd appreciate it.

Thanks,
Warren

Perhaps you could supply an image that shows where your mass points were located as a TIN can only triangulate between points it has (i.e a convex hull). I'm guessing that there is no data in the bottom portion of your soft clip? If this is the case, it might be better to make a TIN for a larger area and then clip that.

Re: Creating TIN with soft clip does not reach full extent of polygon

larryzhang1 — Wed, 13 Nov 2013 02:47:22 GMT

...

model subsurface geology using boreholes--though I'm also combining surface outcrops as well (in the form of high-density elevation points overlaid with geology).

I've noticed a number of my TINs do not fully "fill out" the soft clip polygons I use for them. They may reach only part of the polygon edge and not the full extent.
...

Warren,

Just share ideas, not solution.

What we are doing with boreholes for TIN creation usually includes �??interpolation�?? first, which would help us to model the realistic surface /subsurface (i.e., �??softer and more natural�??).

In fact, the �??covariance / Kriging�?? processes mostly become more important, when dealing with the �??top/bottom�?? points of the geological formations /ore bodies along 'sparse' bores.

As you mentioned, high-density elevation points (LiDAR cloud points ?) are also available. That would help to evaluate the �??new�?? dataset of surface TIN, to check if �??proper�?? interpolation used ...

If sounds true to your case, pls refer to Geostatistics for the details