//-------------------------------------------------------------------------------------------------
static void ParseResultXml(string ResultXml, List <Soil> Soils)
{
XmlDocument XMLdoc = new XmlDocument();
try
{
XMLdoc.LoadXml(ResultXml);
for (int FeatureIndex = 0; FeatureIndex < XMLdoc.GetElementsByTagName("gml:featureMember").Count; FeatureIndex++)
{
XmlDocument XMLdocFeature = new XmlDocument();
XMLdocFeature.LoadXml(XMLdoc.GetElementsByTagName("gml:featureMember").Item(FeatureIndex).InnerXml);
for (int Index = 0; Index < XMLdocFeature.GetElementsByTagName("ms:mukey").Count; Index++)
{
// Skip surface water mapping units
if (XMLdocFeature.GetElementsByTagName("ms:musym").Item(Index).InnerText == "W")
{
continue;
}
Soils.Add(Ssurgo.AddSoil(XMLdocFeature, Index));
}
}
SortedList <String, Soil> UniqueLayerProperties = new SortedList <String, Soil>();
foreach (Soil aSoil in Soils)
{
Ssurgo.GetLayerProperties(aSoil, UniqueLayerProperties);
}
}
catch (Exception)
{
MessageBox.Show("Invalid response from SSURGO web service.");
Ssurgo.FoundValidHSG = false;
}
}
//-------------------------------------------------------------------------------------------------
public static List <Soil> FindSoils(double aLatitude, double aLongitude,
double aDistance = 1000)
{
// Create a list of Soil objects to return
FoundValidHSG = false;
List <Soil> Soils = new List <Soil>();
// Create an HTTP request to get all of the SSURGO mapping units
// within Distance of the target location
string Filter = "<Filter>"
+ " <DWithin>"
+ " <PropertyName>Geometry</PropertyName>"
+ " <gml:Point>"
+ " <gml:coordinates>"
+ aLongitude.ToString()
+ ","
+ aLatitude.ToString()
+ "</gml:coordinates>"
+ " </gml:Point>"
+ " <Distance%20units='m'>"
+ aDistance.ToString()
+ "</Distance>"
+ " </DWithin>"
+ "</Filter>";
string URL = "https://sdmdataaccess.nrcs.usda.gov/Spatial/SDMNAD83Geographic.wfs?Service=WFS&Version=1.0.0&Request=GetFeature&Typename=MapunitPoly&Filter="
+ Filter;
string ResultXml;
// Create a WebClient object to submit the HTTP request
WebClient client = new WebClient();
try
{
// Submit the request and retrieve the response
ResultXml = client.DownloadString(URL);
// Parse the resulting XML with the mapping units info in it
// to obtain boundaries and ultimately soil data for each unit
Ssurgo.ParseResultXml(ResultXml, Soils);
}
catch
{
//MessageBox.Show(e.Message);
throw;
}
client.Dispose();
return(Soils);
}
// Retrieve SSURGO soil data and polygons
public static bool GetSoilData(double lat, double lng)
{
// Initialize soil data
soilPolygons.Clear();
List <Ssurgo.Soil> soils = null;
// Establish a search radius around the site's lat/long
double SoilsSearchRadius = SoilsRadiusIncrement;
double SoilsMaxRadius = 5 * SoilsRadiusIncrement;
// Keep searching the USDA-NRCS's SSURGO DataMart web service within an expanding radius
for (; ;)
{
try
{
// Get soil data within current radius
soils = Ssurgo.FindSoils(lat, lng, SoilsSearchRadius);
}
catch
{
MessageBox.Show("Could not access the SSURGO soils data base.\n" +
"The service may be unavailable.", "Soils Data Search",
MessageBoxButtons.OK, MessageBoxIcon.Information);
return(false);
}
// Data was found
if (soils != null && soils.Count > 0)
{
// Transfer polygons with soil data retrieved from web service to MapPolygon objects
int polyCount = 0;
for (int i = 0; i < soils.Count; i++)
{
polyCount += transferSoilPolygon(soils[i]);
}
if (polyCount > 0)
{
return(true);
}
}
// No data found -- ask user to increase the search radius
if (SoilsSearchRadius < SoilsMaxRadius)
{
string msg = "No soils data were found within a radius of " +
SoilsSearchRadius + " meters. Expand the search?";
if (MessageBox.Show(msg, "Soils Data Search", MessageBoxButtons.YesNo,
MessageBoxIcon.Question) == System.Windows.Forms.DialogResult.No)
{
return(false);
}
SoilsSearchRadius += SoilsRadiusIncrement;
}
// Max. search radius reached
else
{
MessageBox.Show("No soils data were found for this site.", "Soils Data Search",
MessageBoxButtons.OK, MessageBoxIcon.Information);
return(false);
}
}
}