Arcview 9.2 to sketchup pro 6 terrain issues

Arcview 9.2 to sketchup pro 6 terrain issues

Postby clemantine » Sun Apr 13, 2008 1:24 pm

Hello

I'm rather new to Sketchup (been learning for projects at home since Sept 07 and had sketchup pro 6 at work for about a month), more enthusiasm that knowledge sadly, so I'll apologise now if these issues are a bit obvious!

I'm trying to combine the accuracy and precise content of GIS with the accessibility of images in sketchup to create visualisations to be used in a flood alleviation scheme. It's important that the terrain models are as accurate as possible just in case the decisions subsequently made are examined at a later date.

With that in mind I've requested height/elevation data for the whole geographic area that we are looking at and tried to convert it in GIS so that I can use it through the sketchup plugin.

The only data I could get hold of was lidar ascii files. I went through quite a long winded procedure creating a polygon grid as a shapefile (pinpointing xy positions) and extracting z coordinates from the lidar data, joining the two files together which resulted in a shapefile which I could transform into a 'feature class'. I did the same for the buildings using an OS polygon shapefile from which I created point data at the centre of each building and then extracting the z coordinates as before and ultimately created a building feature class.

At this point I should admit that at all points I've been feeling my way forward, my knowledge of GIS had previously been limited to the management and creation of geodatabases which I could use to create reports on features within geographical ares (specifically for me the illustration/reporting of ecological features and the recording of the quality/condition of a site with photos and notes). I haven't had formal training just learnt as I've gone along so there are huge gaps in my knowledge.

When I processed the information through the sketchup plugin I extruded the building feature class - this worked really well :) However, when I asked it to 'elevate' the terrain feature class - this resulted in lots of individually grouped tiles (elevated to the correct height!) - now this looks very interesting, but isn't the 'one-piece' terrain which I had hoped for.

Can anyone help please, I'm feeling around in the dark! Am I using the correct data? Am I treating it in the right way? What's a 'tin'? Where could I get the right data from? What questions should I be asking?

Thank you so much
Clemantine
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Re: Arcview 9.2 to sketchup pro 6 terrain issues

Postby Gaieus » Mon Apr 14, 2008 2:40 pm

Hi Clemantine,

I have no clue about GIS to be honest but of what you wrote, I understand that you have the survey data in an ASCII file. Have a look at Didier's ruby script: "Cloud.rb" which uses such files to create a TIN in SketchUp.

"TIN - Triangulated Irregular Network - A surface comprised of triangles, each derived from irregularly spaced points. This surface is also referred to as a Sandbox and Mesh." [SU Guide]
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Re: Arcview 9.2 to sketchup pro 6 terrain issues

Postby GreyHead » Mon Apr 14, 2008 3:57 pm

Didier's script requires a plain text file with x y z data like

123.456 789.012 234.567
. . .

If you have something like this (decimal places and separators can vary) then it can almost certainly be massaged to work with his script.

Can you post a sample? Or email me the file if you like and I'll take a look 'info at greyhead.net'

Bob
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Re: Arcview 9.2 to sketchup pro 6 terrain issues

Postby ehaflett » Mon Apr 14, 2008 9:41 pm

Clemantine, there are a couple different ways to get your elevation data into SU. A TIN like Gaieus suggests has worked well for me, let me know if you have trouble creating that in GIS and I'd be glad to help, send me a PM. You could also do contours. I haven't used the cloud.rb but based on what I know about LIDAR it's probably your best bet and worth the time to figure out.

What GIS software are you using?
How large is your study area? Large terrain models with a lot of detail can get unwieldy.

Eric
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