Produce information of a line

[JClarke1]

G'day everyone,

I'm using ArcMap desktop 10.6.1. I'm need need of some help. 

I have a dataset of .GPX points which I have converted to .Shp. I have overlaid this onto a DEM and satellite image. What I'm trying to get is information on the line (the line I produced from the .gpx data points) using the underlaid layers. Specifically; lengths, gradient, etc. I tried to use the geometry calculator but received an error message regarding the wrong projection (WGS but required PCS). Furthermore, is it possible to merge the information embedded in the DEM into the satellite imagery to have the satellite imagery? As you can tell I'm quite inexperienced but any advice would help. I've attached a screenshot.

[DavidPike]

I don't know what you mean by merge the DEM into the satellite imagery.

What is the study area? If doing any DEM analysis in ArcMap I would make sure to convert this and the line into a PCS as indicated by the error message.

Use Project—Help | ArcGIS for Desktop for the shapefile and Project Raster—Help | ArcGIS for Desktop for your DEM/DTM.

The extent of the study area and various other considerations will go into your Projection selection.  Common projection would be the UTM zone you are in (if covered by only 1 UTM zone, and Country/State projections).  Custom projection such as Lambert Conformal Conic etc. are also common.

[JClarke1]

Sorry! I know it was an abysmal way of framing my problem. What you said helped. Now another question, how do I, using my line express its gradient in the form of colour change within the lines. 

In other words my line obviously changes gradient as I track along the contours of the hill, I want to express this by a colour change within the line. Is this possible?

[DavidPike]

I've not got great experience in this particular method, but Add Z Information (3D Analyst)—ArcMap | Documentation (arcgis.com) looks useful.

One of the parameters (slope) is calculate per segment of your line (I believe).  So be sure that you're happy with the segments you have at the moment, or perhaps dissolve your current line (if needed) and then use Splitting a line into an equal number of parts—Help | ArcGIS for Desktop or another tool, perhaps, generate points along line at equal distances and then  use those points to split etc.  

be aware that ArcMap isn't clever enough to do geodesic slope calculations (I think still?) so ensure that everything is in the same PCS)

[ABishop]

@JClarke1 

Your questions about displaying the gradient using colors sounds more like a cartographic question?  If your using ArcMap 10.6.1 and are looking to symbolize the features by a range using color, you would do this by setting the symbology for the feature class or shape file.  Here is a quick tutorial I found online:

https://desktop.arcgis.com/en/arcmap/10.6/map/working-with-layers/using-graduated-colors.htm