Problems with lat long projection

Question

Hi this seems like it should be an easy problem, but its been giving me a headache.

I have a .xls spreadsheet with about 60,000 rows. Most of them have Latitude and Longitude. I simply want to display these as points in Arc10.

I've tried making a .dbf in arccatalog and creating a feature class from XY data. The first times I tried this the rows that had no lat/long were given 0,0. The problem is the scale is about 1:1e200+ feet... so the points with correct lat/long are all together but so tiny I can't even zoom into them.

So the second time I just took out all the rows without lat/long. Now the points show up but compared to the old points and the counties they are not lined up and they are tiny...

I've also tried using it as a .csv and as the .xls and in QGIS. I went through all the rows and took out the lat/long points that were entered incorrectly (not in decimal degrees) as well...

On the map there little red point way off where it should be, and it is actually 40,000 points on a scale of 1:19 feet instead of 1:3,000,000ish... The projection is the same as the other layers and when I click on individual points they have the same lat/long, just in different spots.

Answer 1

When someone says that data points are tiny compared to other data layers, the usual problem is that the new points have been assigned a projected coordinate system--probably the one that the other layers are using--but the new points are latitude-longitude and should be assigned a geographic coordinate system.

The Add XY tool will default to the data frame's coordinate system. You need to change that to match what these points are in.

Even though you're seeing latitude-longitude in the data frame, the display units (data frame properties, general tab) may have been set to show degrees or degrees-minutes-seconds even though the data frame's coordinate system is projected.