Line of sight readme improvements (#27)

* Update readme

* reduce the image size

* Apply suggestions from code review

Co-authored-by: Jade Huang <jadehuang@esri.com>

* Apply suggestions from code review

Co-authored-by: Andy Ren <aren@esri.com>
Co-authored-by: Jade Huang <jadehuang@esri.com>

Co-authored-by: Jade Huang <jadehuang@esri.com>
Co-authored-by: Andy Ren <aren@esri.com>

Author: 3 people

sample_project/Content/SampleViewer/Samples/LineOfSight/LineOfSight.jpg

@@ -1,23 +1,30 @@
-# Line of sight
+# Determine the visibility for a line of sight
 
 Determine if the line of sight is obstructed by any object in the scene.
 
 ![Image of line of sight](LineOfSight.jpg)
 
+## How to use the sample
+
+1. Open **LineOfSight** level.
+2. Click on **ArcGISMapActor** in the **Outliner**.
+3. Set your API key in the **Details** panel.
+4. Click play and see the line color change to red if there is any object obstructing the sight.
+
 ## How it works
 
-1. Ensure the box for **Enable Mesh Colliders** on the `ArcGIS Map View` component of `ArcGIS Map Actor` is checked.
-2. Add a `Line of Sight` and a `Way Points` actor to the scene and place them at the desired locations.
-3. Modify the `Path Spline` component of the `Way Points` actor to define the path that the target object is moving along.
-4. The `Line of Sight` actor looks for an instance of `Path Splnie` at `Begin Play` and performs a line trace between them at each frame. 
-5. Any actors that unintentionally interfere with the trace can be added to the `Actors to Ignore` argument of the line trace in the `Line of Sight` blueprint. 
-6. The visual cue for the line of sight changes its color depending on whether the line trace hits the target object or not.
+1. Have an ArcGIS Map with the [mesh collider](https://developers.arcgis.com/unreal-engine/maps/mesh-collider/) enabled.
+2. Have a camera with the [**ArcGIS Camera Component**](https://developers.arcgis.com/unreal-engine/maps/camera/#arcgis-camera-component) attached for the area.
+3. Have an Actor for checking line of sight (**LineOfSight** Actor) and another for defining the path that the target object is moving along (**WayPoints** Actor).
+4. The moiving object's path is defined by [Spline Components](https://docs.unrealengine.com/5.0/en-US/blueprint-spline-components-overview-in-unreal-engine/).
+5. The **LineOfSignt** Actor looks for an instance of the **WayPoints** Actor and performs a [line trace](https://docs.unrealengine.com/5.0/en-US/BlueprintAPI/Collision/LineTraceByChannel/) between them at each frame. 
+    - Any actors that unintentionally intersect the trace can be added to the `Actors to Ignore` of the line trace in the **LineOfSignt** Actor blueprint. 
+    - The visual cue for the line of sight changes its color depending on whether the line trace hits the target object or not.
 
 ## About the data
 
 Building models for New York are loaded from a [3D object scene layer](https://tiles.arcgis.com/tiles/z2tnIkrLQ2BRzr6P/arcgis/rest/services/New_York_LoD2_3D_Buildings/SceneServer/layers/0) hosted by Esri.
 
-WorldElevation3D/Terrain3D
 Elevation data is loaded from the [Terrain 3D layer](https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer) hosted by Esri.
 
 ## Tags