Because your shapefile or feature class isn’t where it’s supposed to be? Surprisingly, it happens more often than we’d like. What should you do when a shapefile is located in the wrong location? When working with ArcGIS projections, you need to run the define projection tool or the project tool. Here is a quick guide highlighting the differences between the ArcMap project tool and the ArcMap define projection tools. “Define Projection” in ArcGIS is what you use when the data has no defined coordinate system. The ArcGIS error message would look like: “Unknown Spatial Reference”. When you run the “Define Projection” tool, the tool does not change the projection. It only changes the metadata describing the current projection of the dataset. The ArcGIS Project tool changes the projected coordinate system of your data to another coordinate system. For example, you have a dataset that is currently in latitude and longitude. If you want to transform this data to NAD 83 UTM Zone 11. The “Project” tool in ArcGIS should be used in this case. Changing the projection by right-clicking an ArcMap will not give the same results as the “Project” tool. You need to run the Project tool in order to change the shapefile. Next time the shapefile is added to ArcMap, it will be projected accordingly. Define projection changes the metadata for the protection that is associated with the file. The ArcGIS Project tool changes the physical coordinate system in the spatial file. It’s important to know when to use each tool in an ArcMap session. Although ArcGIS projections can be confusing at times, we hope this guide gives some clarity to projections in ArcGIS. Does it feel like a big challenge to find LiDAR data sources? Master the art of attaining LiDAR at no cost with this list of 6 free LiDAR data sources. […] If you want free satellite imagery, there’s no better way to do it then follow this incredibly useful guide. We rank the best sources of free satellite data. […] It’s a head-to-head GIS software showdown with the star-studded lineup in the GIS industry- ArcGIS vs QGIS. Discover the differences between ArcGIS and QGIS […] Map all day. Geoprocess all night. All with gvSIG software. gvSIG emerged in 2004. It’s been fine-tuned for over a decade and is used around the world. […] Source.