Correcting Projection in ArcGIS

Importing features into ArcGIS with the correct projection

You may find that you have issues adding a basemap or another dataset when using a feature in ArcMap that was generated in HDFS. This may be because you have not defined a spatial reference.

There are two simple ways to fix this and view your data properly. As you can see in the bottom right corner of ArcMap (when you have added your data), there are unknown units - which is why you will get an error when trying to add a basemap.

##Method 1: Define the data frame projection

This method sets the data frame coordinate system. It will not modify or save the coordinate system of your dataset.

1. Create a new data frame:

   Insert > data frame

2. Set the coordinate System of your data frame:

   Right click the new data frame > Properties > Coordinate Systems > Select your coordinate System (I am using GCS>World> WGS84) > Select OK

3. Add you data to the data frame (press ok if there is an error).

   It will automatically project on the fly - you can now add a basemap or other data.

4. If you want to save your data with this coordinate system, you can:

   right click the feature layer > Data > Export Data > Use the same coordinate system as: the data frame.

A similar method was used in ArcCatalog for our blog post of Vehicle Trip discovery, in ArcCatalog this permanently saves the coordinate system of the feature class.

Method 2: Set the projection of the data

This method defines the projection of the feature layer. It will modify and save the coordinate system of your dataset.

1. Add your data to a new data frame.

2. Use the define projection tool:

   Select your coordinate system (I used GCS>World> WGS84)

3. Copy your data using the Copy tool

   You will now have data with the projection set, ready to use in any map!

More Information

There is a lot of information on Projections at the ArcGIS help pages