Latest Contributions by DavidPetrey1

Ah yes, the new symbol for doesn't equal is !=, though I find <> still works (or is this just a random thing of my installation?), which I usually end up typing out of habit. David ... View more

The code adds a new Data Frame to ArcMap. It works fine on my PC. It may be worth doing this process manually before clicking the 'Yes' button, then remove this code and starting from the line of code 'Dim pMxDoc As IMxDocument' instead. David simplyGIS Ltd. Making GIS simple. www.simplygis.co.uk/GISTraining.html ... View more

I had the exact same problem about a month ago, even with a Float or Double field. I found that exporting my data to a Geodatabase did the trick. David simplyGIS Ltd. Making GIS simple. www.simplygis.co.uk/GISTraining.html If this helped solve your query please mark as answered to let others know. ... View more

Hi, The following might help: -use the Clip tool to clip your lines by your reservoir polygons -Create a new polygon dataset and digitise a polygon large enough to cover all the lines in your original line dataset -Union the new polygon created above with your reservoir polygon dataset, then Start Editing the Union output and Select out the polygons matching your reservoirs polygons and delete them from the Union dataset. Save and Stop Editing. -Next, Clip your original lines with the Union output above. -You should now have 2 line datasets split at the boundaries of your reservoirs. Use the Merge tool to create a single dataset. You might also have to use the Multipart to Singlepart tool to separate any multipart lines. -This process could probably be joined together in ModelBuilder if you needed to repeat it again and again. I hope that helps. It looks like a long process but depending on how large your datasets are it shouldn't take too long. If it helps please mark the question as answered so others are aware. Regards, David simplyGIS Ltd. Making GIS simple. www.simplygis.co.uk/GISTraining.html ... View more

If the raster you are working with is an integer grid then it should have an attribute table with Value and Count so you can simply Select the values between 100-200 and get the Sum of the counts for that field by right clicking on the field name in the attribute table and choosing Statistics. If you have selected values the Statistics just for the selection will appear. If there is no attribute table use the 'Build Raster Attribute Table' Tool for an Integer grid. If your raster has decimal values you will probably need to reclassify it first, making 0-100 a value of 1, 100-200 a value of 2, etc. Then use the attribute table from this to get the counts you need. Hope the above helps. If so please mark the question as answered to let others know. David simplyGIS Ltd. Making GIS simple. www.simplygis.co.uk/GISTraining.html ... View more

Ola, Try the following: -Use the Feature Envelope To Polygon tool to give a bounding box polygon from the buffered dataset (or just create a new polygon dataset and draw a large rectangle that covers all the buffered data). -If you have an ArcInfo/ArcGIS for Desktop Advanced licence simply use the Erase tool. -Otherwise first use the Dissolve tool to create 1 polygon from your buffered data. Then Started Editing the new Envelope dataset. With the Envelope and the Dissolved buffer onscreen Select just the Dissolved buffer polygon and choose Clip from the Editor drop-down menu on the Editor Toolbar. Choose to 'discard the area that intersects' when a message appears and you will be left with your reverse buffer clipped out of your Envelope dataset. If this helps please mark the question as answered to let others know. Thanks, David simplyGIS Ltd. Making GIS simple www.simplygis.co.uk/GISTraining.html ... View more

That seems a bit strange. Whenever I have a weird issue with a dataset I usually try running the Repair Geometry tool from ArcToolbox. This sometimes sorts out geometry issues that can cause problems like this. Alternatively, are you saving and stopping editing before trying to calculate the area of the new polygon? Also, rather than selecting the new polygon on the map, can you select it from the Attribute Table? Finally, try exporting the dataset to a geodatabase first. Area should automatically be added as an attribute to a polygon. Just make sure you are using a Projected Coordinate System. I hope some of the above help. David simplyGIS Ltd - making GIS simple http://www.simplygis.co.uk/GISTraining.html ... View more

Hi, Try adding all the fields you want to use to the first line of the VB script e.g. Function FindLabel ( [Q1_2013] ,[Q2_2013],[Q3_2013] ) Then see if your script works a bit better. Hope this helps. Please mark as answered if it does. David simplyGIS Ltd. Making GIS simple. http://www.simplyGIS.co.uk http://www.simplyGIS.co.uk/GISTraining.html ... View more

Hi, Only just saw this one and thought I would offer up a solution. There are several steps to this: -Get the points representing the towers holding up the wires (these may be the end points of each power line or you may hold them as a separate dataset) and give them an attribute representing the height of the power line at that location (eg 100metres) -Get the mid points between the towers (there are various ways to do this �?? split the power lines in half or use trigonometry with the tower coordinates) and give these a value that the power lines sag down to (eg 80 metres). -Combine the 2 point files into 1 dataset. -Use interpolation such as IDW to create a raster surface using the height values chosen above. -Use the raster surface created as the heights for your power lines in ArcScene. Hope this helps. I actually use this technique in the 3D Analyst course I teach at work. Please mark this as answered if it helped. David simplyGIS Ltd. Making GIS simple. http://www.simplyGIS.co.uk/GISTraining.html http://www.simplyGIS.co.uk/GISTraining/ArcGIS/3D.html ... View more

I had a similar issue with this tool. I also had an issue with the Extract Values to Points tool. If I ran it twice using the previous output the tool would corrupt the values I had extracted the first time. It turned out that the tool could not be run a second time properly because the field name 'RASTERVALU' had already been used as a field name from the first run. I had to create a new field, copy over the values from the first tool run then delete the 'RASTERVALU' field generate by the tool, before running the tool again. In the end I created my own ModelBuilder tool to use the Extract Values to Point tool to act like the Extract Multiple Values to Point tool, which would also create a new field and copy the values over then delete the field 'RASTERVALU' so that it was free for the next run of the tool. Hope that helps. David Simply GIS Making GIS simple ... View more

For creating a path between 2 points: -create a raster with all same values (values of 1) -blank out the land (i.e. make the land all null values) -use the Cost Distance tool with a start point and the single-value, land-masked raster created above to create a Cost Distance raster and a Backlink raster -use the Cost Path tool with the Cost Distance and Backlink Rasters and an input end point -Convert the Cost Path output to a polyline using the Raster to Polyline Tool. -For multiple points I imagine you need to take each point as a start point and get the cost paths to all the other points. Creating the above procedure in ModelBuilder, python or VB/C# would help. -Further analysis options would be to buffer the land or to eliminate shallow water from the study before performing the above analysis as the path will tend to hug the coastline. Or potentially reclassify the various water depths as weights to the cost path creation. Incorporating tidal data to the cost path analysis would add even more sophistication. Hope that all makes sense. David Simply GIS Ltd Making GIS simple. ... View more

Hi, Hopefully the method below should work: Add the smaller IDW dataset as the only input to the calculation for the Raster Calculator tool. Then click the Environments button at the bottom of the tool and go to Processing Extent in the Environment Settings window that appears. Set the Extent to the larger raster dataset. Click OK to set this and then run the Raster Calculator and the output should have null values to the extent you require. David www.simplyGIS.com Making GIS simple ... View more