ogc features over orthophoto over dem

[Tom Rink]

Hi,

Andrea Antonello wrote:

>>>I have huge performance problems, which I hope to resolve somehow later.
>>>      
>>>
>>Probably just big images over lots of topography
>>samples.
>>    
>>
>
>Yes, it is that, but there is no way to deal with it (sorry: I know no
>way). The resampling to merge the flatfields brings the dem to the
>resolution of the photo, which is always high resolution. Some texturing
>would be for sure more performant.
>
>  
>
>>>I hope someone is interested in this first draft and has some ideas on
>>>how to do things better. I welcome all critics (Don Murray, I wasn't yet
>>>able to get things work following your advices, I will come back on that
>>>later).
>>>
>>>I have a couple of rather different questions I would like to post, in
>>>the hope they are not too scattered.
>>>
>>>- in visad, is there some kind of caching system that gives the
>>>possibility to work with huge files that can't be kept in memory? Kind
>>>of tiling mechanism. LIDAR and friends are a now used reality, has
>>>anyone experience?
>>>      
>>>
I'm currently using LIDAR and CLOUDSAT data in the IDV and HYDRA.

>>Some of the file adapter, such as netCDF, do caching,
>>but the do not tile within a FlatField (i.e., not
>>within a single image). They do cache for multiple
>>images, such as in a time sequence.
>>    
>>
>
>Alright, someone in the list working with big datasets? Is there a
>different solution?
>  
>
I have plans to do this for large images - the logic to handle textures 
larger
than the graphics limit will have alot todo with this.

Tom

>  
>
>>>- also, I had to elevate the river of some meter, since in certain parts
>>>it went below the elevation model (which by the way is right, since the
>>>river is made of coarser points as the dem and the lines in some parts
>>>"intersect" the dem). Has anyone a better idea to overlay the shapefile
>>>over the dem?
>>>      
>>>
>>The only alternative is to draw your river in your
>>texture mapped image.
>>    
>>
>
>Agreed.
>
>  
>
>>>- I tried to simulate a line with borders by painting a thinner after a
>>>thicker one of different color. The result is weak as expected, is there
>>>any way to do styling of lines (apart of dashing, which I read is
>>>supported)?
>>>      
>>>
>>You can set a limited number of line styles (i.e.,
>>SOLID_STYLE, DASH_STYLE, DOT_STYLE, DASH_DOT_STYLE)
>>in GraphicsModeControl, or by a ConstantMap to
>>Display.LineStyle.
>>    
>>
>
>I'll have a deeper look into it. Does this include also lines with
>borders?
>
>  
>
>>>And last but not least (even if really not so important :)):
>>>- has anyone an idea about how to put a filled polygon over the dem? I
>>>tried as a joke to do it with Delauny, but it doesn't permit 3D.
>>>Perhaps the best would be to create an image and use it as a texture
>>>over the dem and photo (does this last sentence make a sense?).
>>>      
>>>
>>Yes, construct a FlatField with MathType ((x, y) -> z)
>>and define your IrregularSet (i.e., Delaunay) as its
>>domain Set. Define the "z" range values of your FlatField
>>as the topo level (plus your fudge to keep them above
>>the image) at the corresponding (x, y) locations.
>>    
>>
>
>I'll try that out soon. I'll post the results.
>
>Thanks for your help.
>
>Andrea
>
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>  
>


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