Re: [GRASS-dev] GSOC wk1 checkin

2013-06-23 Thread Hamish
Hi Tim, glad to see you're underway.

is it possible to post some data samples on your project's blog? (a description 
+ figure would be great) It would help to get a better idea of what the import 
options would be for those three datasets. What form is the Natural Resources 
Conservation Service survey data in?
If you like/need I can poke around here for some more datasets.

 My work product next week is going to focus on the interpolation
 module. The abstract workflow for the module as whole is as follows

 Process for generation of r3 voxel grid from a population of xy
 located 1 dimensional horizon descriptions
  1. Import of database horizon descriptions
  2. Generation of line vector representing the path of the horizon
  description in xyz

note that GRASS vector lines can not store per-vertex attribute data,
only per-line attribute data. Anything else must be stored as points;
see the v.in.gps module. one idea is to trick the vector engine into storing 
depth vs. value1 [vs. value2] in x,y[,z] structure. then translate out the 
results at the last step when you need real earth-coord x,y,z.
?

  3. Segmentation of the line vector into n number xyz points

so binning by depth segment?

  4. query of attribute values to points from attribute database
  5. Generation of r3 region
  6. Interpolation of point attribute values through geostatistical
   and/or logical operators onto voxel grid locations

wrt to single x,y location well log, it seems to me like the r3.in.xyz
module already gives you most of that, bypassing the vector line stage
completely. binning 3D data into voxels using univariate statistics is 
precisely what it does.

are you looking to interpolate/aggregate vertically first, then
horizontally? would you interpolate at each depth band separately
then combine those together?

how well does that work with dipping angles? perhaps v.vol.rst could help too, 
to interpolate everything at once in a more 3D-influenced model?

 One point that Ben articulated was that the interpolation assignment
 needs to be capable of operating on integer data so that it can work
 on

that got cut off, but I guess you mean categorical value, so nearest
neighbour is needed, and not linear, cubic, or spline.

 Best wishes on this first day of summer. 

Up to my knees in snow yesterday, but good mountain boots and funner than the 
rain and sleet that was falling down in the valley. :)


regards,
Hamish

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Re: [GRASS-dev] GSOC wk1 checkin

2013-06-23 Thread Pierre Roudier
Hi Tim, Hamish et al.,

Just jumping in the discussion, FYI: I am following the project with
much attention, in particular because I am working with soil data,
both at the national scale in NZ, but also on international project
that aim at storing important amounts of data [www.globalsoilmap.net].

The soil science community has recognised the difficulty to deal with
the storage of soil horizon data, and a specific working group has
been formed under the auspices of the International Union of Soil
Sciences [www.soilinformationstandards.org/content/about].

We've already been developing data models for storing soil data, I'd
be happy to point you towards these if that is of interest for your
project.

Tim, all the best for your summer project,
Hamish, hang on tight for this cold winter blast!

Talk soon,

Pierre


2013/6/23 Hamish hamis...@yahoo.com:
 Hi Tim, glad to see you're underway.

 is it possible to post some data samples on your project's blog? (a 
 description + figure would be great) It would help to get a better idea of 
 what the import options would be for those three datasets. What form is the 
 Natural Resources Conservation Service survey data in?
 If you like/need I can poke around here for some more datasets.

 My work product next week is going to focus on the interpolation
 module. The abstract workflow for the module as whole is as follows

 Process for generation of r3 voxel grid from a population of xy
 located 1 dimensional horizon descriptions
  1. Import of database horizon descriptions
  2. Generation of line vector representing the path of the horizon
  description in xyz

 note that GRASS vector lines can not store per-vertex attribute data,
 only per-line attribute data. Anything else must be stored as points;
 see the v.in.gps module. one idea is to trick the vector engine into storing 
 depth vs. value1 [vs. value2] in x,y[,z] structure. then translate out the 
 results at the last step when you need real earth-coord x,y,z.
 ?

  3. Segmentation of the line vector into n number xyz points

 so binning by depth segment?

  4. query of attribute values to points from attribute database
  5. Generation of r3 region
  6. Interpolation of point attribute values through geostatistical
   and/or logical operators onto voxel grid locations

 wrt to single x,y location well log, it seems to me like the r3.in.xyz
 module already gives you most of that, bypassing the vector line stage
 completely. binning 3D data into voxels using univariate statistics is 
 precisely what it does.

 are you looking to interpolate/aggregate vertically first, then
 horizontally? would you interpolate at each depth band separately
 then combine those together?

 how well does that work with dipping angles? perhaps v.vol.rst could help 
 too, to interpolate everything at once in a more 3D-influenced model?

 One point that Ben articulated was that the interpolation assignment
 needs to be capable of operating on integer data so that it can work
 on

 that got cut off, but I guess you mean categorical value, so nearest
 neighbour is needed, and not linear, cubic, or spline.

 Best wishes on this first day of summer.

 Up to my knees in snow yesterday, but good mountain boots and funner than the 
 rain and sleet that was falling down in the valley. :)


 regards,
 Hamish

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-- 
Scientist
Landcare Research, New Zealand
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Re: [GRASS-dev] GSOC wk1 checkin

2013-06-22 Thread Martin Landa
Hi Tim,

thanks for your report. Just small reminder that this report should be sent
in copy also to `s...@lists.osgeo.org` ML.

Martin
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