Methods Of Making A Base Map

There’s a couple of ways you can make a base map: 

1. Trilateration – the most low tech, effective solution 

2. Tracing an aerial photo at scale 

3. Using software to make a digital base map 

1) Using Trilateration to Make a Base Map 

Trilateration is the process of determining the locations of points by measurement of distances, using the geometry of circles and triangles. Trilateration is an easy way to survey a small block of land or a back yard. It does not require special training and only requires a few inexpensive tools. Tools which will need for trilateration: 

In the field: 

1. A tape measure (20 m long is usually enough) 

2. A sketch pad or grid paper for recording your measurements 

3. Some drafting pencil or pens. 

Back inside 

1. A nice large sheet of paper to make your base map on 

2. Some drafting pencil or pens. 

3. A drawing compass (Preferably with an extension arm) 

4. A scale rule 

2) Tracing an Aerial Photo at Scale 

It is one of the quickest ways is to project a satellite image or aerial photo onto your paper and trace it. To do this: 

• Choose an image with a scale bar visible e.g. in the bottom right 
• Choose the scale by adjusting the zoom of the projector (or moving it closer or further from the wall) until the site fits on the page and the scale bar measures true on a scale ruler 
• Read the scale off the ruler (e.g. 1:50) 
• Trace the major features off the projection onto the page. 

3) Creating a Digital Base Map 

Another way is to use software on a computer to create a digital base map from a satellite image or aerial photo. 

Base map is a layer with geographic information that serves as a background. A base map provides context for additional layers that are overlaid on top of the base map. Base maps usually provide location references for features that do not change often like boundaries, rivers, lakes, roads, and highways. Even on base maps, these different categories of information are in layers. Usually a base map contains this basic data and then extra layers with a particular theme or from a particular discipline, are overlaid on the base map layers for the sake of analysis. 

Some base maps look like Vector Layers but are actually tiled Raster layers. Tiled images are used because they display faster and deliver a good combination of layers for providing context and orientation. If your base map has raster layers, you cannot turn the layers off and on. For example, if you wanted to show all the different types of endangered plants within a region, you would use a base map showing roads, provincial and state boundaries, waterways and elevation. Onto this base map, you could add layers that show the location of different categories of endangered plants. One added layer could be trees, another layer could be mosses and lichens, another layer could be grasses.