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Matt Wilson
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| Joined: | Tue Aug 12th, 2008 |
| Location: | Hobart, Australia |
| Posts: | 66 |
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Posted: Thu Jan 15th, 2009 04:02 am |
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There have been a number of questions raised about the use of Scene views for visualizing data that is specified in (latitude, longitude) coordinates.
The basis of all of the questions is that Scene views use the same units for the three spatial axes axes. Hence specifying scene contents in degrees of arc on the X and Y axes and in metres on the Z axis results in a scale mismatch of the order of 100,000.
The mismatch can be partially rectified by modifying the vertical exaggeration of the Scene view. Using a vertical exaggeration of 0.00001 will make the visualizers appear properly scaled.
However, the radius setting for 0D points and 1D lines visualizers is also specified in these common coordinates, so a radius of one degree corresponds to approximately 100,000 metres.
This mismatch can also be rectified by modifying the radius setting appropriately, using a value of 0.00001 multiplied by the desired radius in metres.
The sizes of haloes need to be specified separately for X, Y and Z axes if the contents of the Scene view are in (latitude, longitude) coordinates. X and Y halo sizes must be specified in degrees of arc, the Z halo size in metres.
The ideal solution however is to reproject the data so that all of the three spatial axes are specified in metre units.
This can be achived by:
- Setting projections as part of the metadata for the data sets that are input to the Scene view.
- Setting a projection as part of the Scene view's axis definition.
All input vector data sets will then be automatically reprojected for display in the scene. Reprojecting data into coordinates with a common unit will solve the problems with vertical exaggeration, vsiualizer radii and halo size described above.
See the following pages in the manual for more information:
http://eonfusion2.myriax.com/manual/index.php/Project_data
http://eonfusion2.myriax.com/manual/index.php/Scene_properties
Note that raster data sets cannot be reprojected in version 1.1 of Eonfusion. However the ability to do so will be added in the near future.
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anager
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Posted: Thu Oct 22nd, 2009 07:06 pm |
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In Version 2.0, can you now map raster images onto bathymetry data (lat, lon, z) in WGS84? When I try to map the image within the visualizer while using a WGS84 projection, I receive an error event saying that "Attribute "X" is not regular. All I'm attempting to do is drape a geotiff onto a bathymetry scene in an angular units based scene. I have specified a grid of cells for the interpretation and specified all my color categories. I also read my data in the correct datum but switched to WGS with a metadata operator later. Any ideas?
On a similar note, if my geotiff resolution is adequate, is there a way to copy the lat/lon matrix from my geotiff geodetic info file into my bathymetry vector and have Eonfusion interpolate the Z values? The idea of this would be to sync the values of the geotiff and bathymetry file to make for easy plotting because then the interpolation wouldn't alter the values that are indexed in the geotiff.
Thanks.
- Andy Nager, Scripps Institution of Oceanography
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Warwick Gillespie
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| Joined: | Wed Nov 5th, 2008 |
| Location: | Hobart, Australia |
| Posts: | 26 |
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Posted: Fri Oct 23rd, 2009 02:48 am |
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Hi Andy,
When you reproject a Raster the attributes that are transformed will no longer be regular and can`t be used to map the raster onto a vector surface or Raster DEM (see http://www1.eonfusion.com/manual/index.php/Rasters#Raster_axes_and_regularity).
Instead of reprojecting the raster, set the projections for the raster image and vector bathy at the source, if necessary reproject the vector bathy to the same as the raster image, then set the desired scene projection in the scene properties.
Another option, instead of reprojecting your bathy (which has attributes lon,lat,z) in the dataflow you could use the Copy Attributes operator to create a copy of the lon,lat attributes renamed as x,y and reproject the x,y attributes to the same projection as the raster image. Then in the scene you can use the lon,lat attributes on the X,Y axis of the scene to visualize the bathy, but use the x,y attributes for mapping the raster image onto the vector surface.
I am not sure what you mean in the second part of you question, can you provide any more details?
Hope this has helped.
cheers,
Warwick
Last edited on Fri Oct 23rd, 2009 02:49 am by Warwick Gillespie
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anager
Member
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Posted: Mon Oct 26th, 2009 04:49 pm |
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Hi Warwick,
Thank you so much for your help. That second idea worked beautifully.
The second question is essentially a more complicated way of asking for your second solution. Sorry for the confusion.
Thanks again.
- Andy
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