Wednesday, May 24, 2017

When to use ArcGIS Online to publish geospatial data: CASE STUDY EUROPEAN ENVIRONMENT AGENCY

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ArcGIS Online is a workspace and a web platform for creating and sharing maps. It is possible to upload your data, create a layer or a map, define the extent, set some visualization options, assign permissions to your layer or map, share, and create web mapping applications or story maps. For information about the other capabilities please visit http://doc.arcgis.com/en/arcgis-online/.

The ArcGIS online platform is designed to host small datasets, for example demographic datasets. The datasets uploaded to ArcGIS online are relatively small in size, and should not exceed 1-2MB, or around 5000 records. This is to keep the agencies costs down and keep in line with our ArcGIS online pricing plan. It is for this reason that ArcGIS online should not be used to host large datasets, and tiled image services must NOT be uploaded to ArcGIS online. To publish bigger datasets and image services, please refer to the ArcGIS Server.

Source: http://discomap.eea.europa.eu/map/giseionet/Publishing_data_to_the_web_with_ArcGIS_Online.pdf

Wednesday, May 17, 2017

Code snippet: Identify to which polygon a point belong to?

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Code sample to find point inside a polygon in shape file using GDAL/OGR 2.x and C#.


using OSGeo.OGR;
using OSGeo.OSR;
using OSGeo.GDAL;
1:  public void FindPolygonBelongsToPoint()   
2:      {  
3:        try   
4:        {  
5:          var shapePath = @"C:\Locations_WGS84.shp";  
6:          Ogr.RegisterAll();  
7:          OSGeo.OGR.Driver shapeDriver = Ogr.GetDriverByName("ESRI Shapefile");  
8:          DataSource shape = shapeDriver.Open(shapePath, 0);  
9:          Layer layer = shape.GetLayerByIndex(0);  
10:    
11:          Feature polygonFeature = layer.GetNextFeature();  
12:    
13:          long featureCountInLayer = layer.GetFeatureCount(1);  
14:          for (int i = 1; i <= featureCountInLayer; i++) {  
15:    
16:            Geometry polygonGeom = polygonFeature.GetGeometryRef();  
17:    
18:            string coordinates = "POINT (-100.726 38.995)";  
19:    
20:            SpatialReference spatialRef = layer.GetSpatialRef();  
21:            Geometry point = Ogr.CreateGeometryFromWkt(ref coordinates, spatialRef);  
22:    
23:            bool isInside = point.Within(polygonGeom);  
24:    
25:            if (isInside)  
26:            {  
27:              var val = polygonFeature.GetFieldAsString(4);  
28:              Console.WriteLine("Found one");  
29:            }  
30:    
31:            polygonFeature = layer.GetNextFeature();            
32:          }         
33:            
34:        }  
35:        catch (Exception ex)   
36:        {  
37:    
38:          Console.WriteLine(ex.Message);  
39:        }          
40:        
41:      }  

Tuesday, May 2, 2017

Code snippet: To highlight selected feature in ArcMap programmatically using ArcObjects

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Code snippet to highlight selected feature in ArcMap programmatically using ArcObjects and return the STGeomFromWKB   string of selected feature.

To return the geometry you should import Microsoft.SqlServer.Types  from Nuget and SqlServerSpatial140.dll  from C:\Windows\System32

 using System;  
 using System.Collections.Generic;  
 using System.Data.SqlTypes;  
 using System.Linq;  
 using System.Runtime.InteropServices;  
 using System.Text;  
 using System.Windows;  
 using ESRI.ArcGIS.ArcMapUI;  
 using ESRI.ArcGIS.Carto;  
 using ESRI.ArcGIS.Catalog;  
 using ESRI.ArcGIS.CatalogUI;  
 using ESRI.ArcGIS.Desktop.AddIns;  
 using ESRI.ArcGIS.Display;  
 using ESRI.ArcGIS.esriSystem;  
 using ESRI.ArcGIS.Framework;  
 using ESRI.ArcGIS.Geodatabase;  
 using ESRI.ArcGIS.Geometry;  
 using Microsoft.SqlServer.Types;  
   
   
 namespace Test.Addin.ArcCommands  
 {  
   class SelectFeatureTool : ESRI.ArcGIS.Desktop.AddIns.Tool  
   {  
     protected override void OnMouseDown(MouseEventArgs arg)  
     {  
       IMxDocument mxDocument = ArcMap.Application.Document as IMxDocument;  
       IActiveView activeView = mxDocument.ActiveView;  
       IMap map = mxDocument.FocusMap;  
       ILayer layer = map.get_Layer(0); //Get 1st Layer  
       IFeatureLayer featureLayer = (IFeatureLayer) layer;  
   
       IPoint identifyPoint = activeView.ScreenDisplay.DisplayTransformation.ToMapPoint(arg.X, arg.Y);  
       ESRI.ArcGIS.Carto.IIdentify identifyLayer = (IIdentify)layer;  
       IArray array = identifyLayer.Identify(identifyPoint);  
         
       int oid = -1;  
       if (array != null)  
       {  
         object obj = array.get_Element(0);  
         IFeatureIdentifyObj fobj = obj as IFeatureIdentifyObj;  
         IRowIdentifyObject irow = fobj as IRowIdentifyObject;  
         IFeature feature = irow.Row as IFeature;  
         oid = feature.OID;  
       }  
       HighlightClickedFeature(featureLayer, oid, activeView);  
     }  
   

Python code snippet : Merge multiple CSVs (Column Wise) into a large CSV file using ID

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Following is the python code snippet to merge multiple CSVs into a large CSV (column wise) using CSV's unique ID field. All input CSV's must have same length.

 import csv
 import itertools
 
 outCombinedStatTxtName ="FormattedTxtResults.csv"  
 tempCsvFiles = glob.glob(str(TempFolderPath)+'\*.csv')  
 openedFileList = [open(fn, 'rb') for fn in tempCsvFiles]  
 readers = [csv.reader(fn) for fn in openedFileList]  
   
 result = open(outCombinedStatTxtName, 'wb')  
 writer = csv.writer(result,delimiter=',')  
   
 multipleIndices = False  
 for row_chunks in itertools.izip(*readers):  
   tempFormattedRow = list(itertools.chain.from_iterable(row_chunks))  
   fidIndices = [i for i, x in enumerate(tempFormattedRow) if x == "ID"]  
   if(len(fidIndices) > 1):  
     fidIndices.pop(0)  
     redundantIndices = tuple(fidIndices)  
     multipleIndices = True  
       
   if(multipleIndices):  
     tempFormattedRow = [ tempFormattedRow[i] for i in xrange(len(tempFormattedRow)) if i not in set(redundantIndices) ]      
     writer.writerow(tempFormattedRow)  
   else:  
     writer.writerow(tempFormattedRow)  
 result.close()     
 [fn.close() for fn in openedFileList]  


Friday, April 14, 2017

Code Snippet: Select feature polygon(s) on Mouse Click ArcObjects C#

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Code snippet of custom feature(s) selection tool on mouse click and highlight it using ArcObjects and C#.

 class SelectFeatureTool : ESRI.ArcGIS.Desktop.AddIns.Tool  
   {  
     protected override void OnMouseDown(MouseEventArgs arg)  
     {  
       IMxDocument mxDocument = ArcMap.Application.Document as IMxDocument;  
       IActiveView activeView = mxDocument.ActiveView;  
       IMap map = mxDocument.FocusMap;  
       ILayer layer = map.get_Layer(0); //Get 1st Layer  
       IFeatureLayer featureLayer = (IFeatureLayer) layer;  
   
       IPoint identifyPoint = activeView.ScreenDisplay.DisplayTransformation.ToMapPoint(arg.X, arg.Y);  
       ESRI.ArcGIS.Carto.IIdentify identifyLayer = (IIdentify)layer;  
       IArray array = identifyLayer.Identify(identifyPoint);  
         
       int oid = -1;  
       if (array != null)  
       {  
         object obj = array.get_Element(0);  
         IFeatureIdentifyObj fobj = obj as IFeatureIdentifyObj;  
         IRowIdentifyObject irow = fobj as IRowIdentifyObject;  
         IFeature feature = irow.Row as IFeature;  
         oid = feature.OID;  
       }  
       HighlightClickedFeature(featureLayer, oid, activeView);  
     }  
   

Wednesday, March 22, 2017

Catch Exception - Attempted to read or write protected memory in ESRI ArcObjects .Net 4.0 Framework

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First - Don't write the code to throw "Attempted to read or write protected memory" ..it is bad.

Second - If you are working on legacy codes and COM objects that throws "Attempted to read or write protected memory" while writing ArcMap add-ins, catch exceptions to prevent application crash, in my case ArcMap.


Step #1 - Add following snippet to config file - app.config for Arc-addin

<configuration>
   <runtime>
      <legacyCorruptedStateExceptionsPolicy enabled="true" />
   </runtime>
</configuration>
Step #2

Add -

[HandleProcessCorruptedStateExceptions] 
[SecurityCritical]
on the top of function you are tying catch the exception

[HandleProcessCorruptedStateExceptions]
[SecurityCritical]
public IFeatureLayer GetOrCreateFeatureLayer(string path, esriGeometryType type, ISpatialReference sr)
{
//body
}

Thursday, March 16, 2017

Good compatibility of latest vagrant and virtual box

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Continuing from my older post  on Vagrant 1.7.2 / 1.9.2 and Virtualbox 4.3.12  / 5.1.14. I upgraded into Vagrant 1.9.2 and 5.0.x and 5.1.x , because of security vulnerabilities on those Virtualbox versions, but my shell provisions and puppet provision that used to work on old setting suddenly stopped working and tried various workaround to make them working but failed until Virtualbox 5.1.18. I use chocolaty, to upgrade/install vagrant and virtual box in Windows 7 host and able to fire 'vagrant up' to provision my new guest.

Step 1

Install chocolaty in host machine using cmd.exe (Run elevated)
@powershell -NoProfile -ExecutionPolicy Bypass -Command "iex ((New-Object System.Net.WebClient).DownloadString('https://chocolatey.org/install.ps1'))" && SET "PATH=%PATH%;%ALLUSERSPROFILE%\chocolatey\bin"
      choco -v (Just to make sure chocolaty installed correctly)
      
      0.10.3 (as of 3/16/2017)

    Step 2
    Open Windows' power shell (Run elevated) 
    1. Install or upgrade oracle virtual box

    choco install virtualbox -version 5.1.18
                                                                                                             5.1.18 r114002
    choco upgrade virtualbox

    2. Install or upgrade vagrant

    choco install vagrant -version 1.9.2

    choco upgrade vagrant

    3. Restart the machine
    4. Vagrant up ....Boom all old scripts starting work again!

    Wednesday, February 15, 2017

    List of things appropriate and not appropriate for ArcGIS from Citrix Environment

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    Appropriate for Citrix
    ·         making maps with existing data
    ·         querying and selecting spatial data
    ·         creating GIS points from XY coordinates (GPS files)
    ·         Sub -setting data by selection and export
    ·         Creating or editing GIS data feature by feature
    ·         Buffering small data layers (few features, simple features)
    ·         Joins on attribute tables
    Not Appropriate for Citrix
    ·         Geoprocessing (Intersect, Union, Identity …)
    ·         Sub -setting data by Clipping
    ·         Spatial joins
    ·         Spatial Analyst
    ·         Buffering large or complex data layers

    Thursday, January 19, 2017

    Code snippet : Create/update polygon attribute fields using Ogr and ESRI Arcobjects

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    A code snippet example to check if a feature is standalone ESRI Shape or featureclass inside ESRI Gdb, then add new filed or update attribute value in attribute table .... standalone shape/features are created/updated using GDAL/OGR implementation and feature/featureclass stored in ESRI personal GDB are created/updated using ESRI ArcObjects.  Any solution to replace later with GDAL/Ogr is highly appreciated.  Please comment below if you find one.

     public void AddUpdateAttributeField(string oldFeatureFile)  
         {  
           DriverUtils.RegisterOgrDriver();  
           DataSource dataSource;  
           Layer layer;  
           var isShapeFile = IsShapeInGdb(oldFeatureFile);  
           if (isShapeFile)  
           {  
             dataSource = Ogr.Open(oldFeatureFile, 1); //second argument in open specifies mode of data, 1 RW & 0 readonly mode  
             layer = dataSource.GetLayerByIndex(0);  
             FieldDefn gdalFiedlDefn = new FieldDefn("FID_GDAL",FieldType.OFTInteger);  
             layer.CreateField(gdalFiedlDefn, 0);  
             Feature feature = layer.GetNextFeature();  
             while (feature!= null)  
             {  
               feature.SetField("FID_GDAL",feature.GetFID()); // Add FID shapefile  
               layer.SetFeature(feature);  
               feature = layer.GetNextFeature();  
             }  
             dataSource.FlushCache();  
           }  
           else  
           {  
             try  
             {  
               EnableEsriLiscences();  
               string gdbPath = Path.GetDirectoryName(oldFeatureFile);  
               string featureName = Path.GetFileNameWithoutExtension(oldFeatureFile);  
               IWorkspaceFactory workspaceFactory = new FileGDBWorkspaceFactory();  
               IFeatureWorkspace featureWorkspace = (IFeatureWorkspace)workspaceFactory.OpenFromFile(gdbPath, 1);  
               IFeatureClass featureClass = featureWorkspace.OpenFeatureClass(featureName);  
               IFields fields = featureClass.Fields;  
               if (fields.FindField("FID_GDAL") == -1)  
               {  
                 // Create a Int field called "FID_GDAL" for the fields collection

    Friday, January 13, 2017

    Code snippet: Create new Field in a Shape File using GDAL/OGR in C#

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    Add new field in existing shape file using OGR in C#.
     public void AddAttributeField(string oldShapeFile)  
         {  
           Ogr.RegisterAll();  
           DataSource dataSource = Ogr.Open(oldShapeFile, 1); //second argument in open specifies mode of data, 1 RW & 0 readonly mode  
           Layer layer = dataSource.GetLayerByIndex(0);  
           FieldDefn gdalFiedlDefn = new FieldDefn("NEW_FIELD",FieldType.OFTInteger);  
           layer.CreateField(gdalFiedlDefn, 1);  
           Feature feature = layer.GetNextFeature();  
           while (feature!= null)  
           {  
             feature.SetField("NEW_FIELD",feature.GetFID()); // Populate new field with feature FID  
             layer.SetFeature(feature);  
             feature = layer.GetNextFeature();  
           }  
           dataSource.FlushCache();  
         }  
    
     

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