Create grid of points with arbitrary coordinate system, add elevation data to points

Question

Hi all,

I have a 2 sq metre microscale hydraulic model of a river, and have been using a laser rangefinder to detect elevation changes on an overhead rail, every 5 cm east/west and 5 cm north/south (a grid of elevation spot heights).

Is there a way to represent these spot heights as point data with elevation values; effectively creating a coarse raster in ArcMap?

How can an arbitrary coordinate system be assigned to these points, so they are in positions relative to reality? (through scaling)

Sorry for all of the questions, I am by no means a GIS expert, but can figure it out if guided to relevant help topics.

iuriherzfeld · Answer

Hi.  I have a somewhate related question

I need to make an airplane approximation surface.  For this I need to make the polygon vertices be at different heights (not bound to any known surface).  Do not seem to be able to do this in ArcGIS.  I am sure in CAD this would be really simple.  Help please as I am not a CAD user.

JeffreySwain · Answer

So you have a series of points, collected at 5 cm increments and are looking to create a raster?  You could try a Spline to interpolate between the points, or if you have 3d Analyst you could create a TIN or Terrain to visualize it.  Each would create a continuous surface.  I suggested the Spline to rubbersheet and maintain the heights at the point.  Does that help?  It might also be interesting to convert the points to 3d and visualize in ArcScene to see if there are any issues with the data prior to interpolation.

BlairCampbell · Answer

Thankyou for your reply Pavan!

The elevation data are stored in a spreadsheet. I might need to explain the setup further.

I have a 2 m wide by 5 m long tilted 'table', with water and sediment feeders at the upstream end, and polystyrene inserts representing landforms/river channel boundaries. At the downstream end, water is re-circulated to a header tank.

This microscale model is scaled 1:5000 from its prototype river, thus is geometrically similar. To measure elevation, I have a steel bar with supports that is positioned horizontally over the model; attached to it is a builders laser rangefinder pointed towards the sediment.

I move the rangefinder in east/west directions every 5 cm for elevation transects, then move steel bar 5 cm south, and repeat another transect. Thus I have elevation points (e.g. 30.1 cm, distance from rangefinder from sediment). As the riverbed aggrades, the next measurement at the same point will be (e.g. 29.5 cm) to the sediment.

In the Excel spreadsheet, I have this grid of elevation points, and I am visualising that in ArcMap there might be a way to create a 'raster' of point feature classes, with a coordinate system (based on the model scale) that matches an elevation point to the corresponding position in reality.

Can it be done? I appreciate everyone's time or interest.

Blair.