[OSM-talk] Kosmos v1.3 - shaded relief

[Artem Pavlenko]

Hi Igor,

Thanks very much for shaded relied algos. I didn't have a chance to  
look, yet, but I sure will.

Cheers
Artem
On 13 Jan 2008, at 17:50, Igor Brejc wrote:

> Artem Pavlenko wrote:
>>
>> AFAIK, all freely available void-filled SRTMs are not free. At  
>> least there's 'for non-commercial use only' clause attached.
>>
> Yes, that's true. When I find the time I will examine the sources  
> and try to contact authors to ask them permission to use their  
> data. As for the "non-commercial use", since Kosmos itself is by  
> currently licensed for non-commercial use only, I don't think that  
> should be a problem.
>>
>> Yes, please. I'm very interested in new ideas for generating  
>> reliefs and filling voids.
>>
>> Anyways, great stuff!
>>
>> Cheers
>> Artem
> I've attached source files for all of the shading algorithms used  
> in Kosovo. I plan to add some more (like elevation coloring) in the  
> future. I hope the source code helps - I've included all the  
> relevant stuff. If you have any questions or suggestions, please  
> feel free to write. I saw your work on DEM processing and I'm  
> impressed. I too am interested in new ideas :)
>
> Regards,
> Igor<Shading.zip>using System;
> using System.Collections.Generic;
> using System.Text;
> using System.Drawing;
> using System.Diagnostics.CodeAnalysis;
> using log4net;
> using Brejc.DemLibrary.Shading;
>
> namespace Brejc.DemLibrary
> {
>     public sealed class DemProcessor
>     {
>         static public Image GenerateShadedReliefImage (
>             IRasterDigitalElevationModel dem,
>             IShadingMethod shadingMethod,
>             ShadingParameters shadingParameters)
>         {
>             Bitmap bitmap = new Bitmap (dem.LonLength, dem.LatLength);
>
>             double[][] window = new double[3][] { new double[3],  
> new double[3], new double[3] };
>
>             double earthRadius = 6360000;
>             double earthCircumference = earthRadius * 2 * Math.PI;
>             double latSpacing = earthCircumference / (360 *  
> dem.LatResolution);
>
>             shadingMethod.Initialize (shadingParameters);
>
>             for (int y = 1; y < dem.LatLength - 1; y++)
>             {
>                 GeoPosition geoPos = dem.GetGeoPosition (0, y);
>                 double lonSpacing = earthCircumference / (360 *  
> dem.LonResolution) * Math.Cos (geoPos.Latitude * Math.PI / 180.0);
>
>                 for (int x = 1; x < dem.LonLength - 1; x++)
>                 {
>                     GetMovingWindow (dem, window, x, y);
>
>                     double dzdx = ((window[0][0] + 2 * window[0][1]  
> + window[0][2])
>                         - (window[2][0] + 2 * window[2][1] + window 
> [2][2]))
>                         / (8 * lonSpacing);
>
>                     if (double.IsNaN (dzdx))
>                         continue;
>
>                     double dzdy = ((window[0][0] + 2 * window[1][0]  
> + window[2][0])
>                         - (window[0][2] + 2 * window[1][2] + window 
> [2][2]))
>                         / (8 * latSpacing);
>
>                     if (double.IsNaN (dzdy))
>                         continue;
>
>                     double riseRun = Math.Sqrt (dzdx * dzdx + dzdy  
> * dzdy);
>                     double slope = Math.PI / 2 - Math.Atan (riseRun);
>
>                     double aspect = Math.Atan2 (dzdy, dzdx);
>
>                     //double aspect = Math.Atan2 (window[1][0] -  
> window[1][2],
>                     //    window[0][1] - window[2][1]);
>
>                     if (dzdx != 0 || dzdy != 0)
>                     {
>                         if (aspect == 0)
>                             aspect = Math.PI * 2;
>                     }
>                     else
>                     {
>                         aspect = 0;
>                     }
>
>                     Color color = shadingMethod.CalculateColor  
> (aspect, slope);
>
>                     bitmap.SetPixel (x, bitmap.Height - y, color);
>                 }
>             }
>
>             return bitmap;
>         }
>
>         static private void GetMovingWindow  
> (IRasterDigitalElevationModel dem, double[][] window, int x, int y)
>         {
>             for (int xi = -1; xi <= 1; xi++)
>                 for (int yi = -1; yi <= 1; yi++)
>                     window[xi + 1][yi + 1] =  
> dem.GetElevationForDataPoint (x + xi, y + yi);
>         }
>
>         private DemProcessor () { }
>
>         [SuppressMessage ("Microsoft.Performance",  
> "CA1823:AvoidUnusedPrivateFields")]
>         static readonly private ILog log = LogManager.GetLogger  
> (typeof (DemProcessor));
>     }
> }