7 Geoprocessing Tools Every GIS Analyst Should Know

Geoprocessing and GIS Tools
7 GIS Processing Tools Every GIS Analyst Should Know

Learn These Essential Geoprocessing Tools

So you want to geoprocess like a GIS guru, do you? Well, these 7 geoprocessing tools always top the chart in the GIS guru’s hit list. They’re our bread and butter.

From clipping to buffering, you will learn the basics of processing GIS data. And you will get a better understanding how these GIS tools are used in the real world.

What are the most used geoprocessing tools in the GIS industry? For newbies in GIS, these 7 GIS processing tools we recommend you learn like the back of your hand.

Ready to get started?

1 The Buffer Tool

Keep your distance. Stay 5 meters away at all times.

How do you create a constant distance away from something? The answer? Run a buffer!

Buffer Line
The buffer tool is a proximity function that sets a fixed or variable distance surrounding the feature(s).

The  Buffer Tool  is a proximity function. When you use this geoprocessing tool, it creates a polygon at a set distance surrounding the feature(s). A buffer is a polygon or collection of cells that are within a specified proximity of a set of features.

How is the Buffer Tool Used in GIS?

  • Add a point, line or polygon feature.
  • Set a buffer distance.

Buffer Tool Example: Keeping Your Distance With the Chernobyl Exclusion Zone




Chernobyl is the worst nuclear disaster in human history.

It released hundreds of times more radiation than Hiroshima. It is one of only two classified as a level 7 event (the maximum classification). Surrounding vegetation absorbed radioactive isotopes and died within a week of the blast.

As a result of the deadly toxins released in the atmosphere, a 2600 square kilometer buffer around the nuclear power plant was declared. This buffer zone is still in effect and it’s called the Chernobyl exclusion zone.

Chernobyl Exclusion Zone
After the Chernobyl nuclear explosion, a buffer radius of 18.6 miles (30 km) was setup as the Chernobyl Exclusion Zone.

30 years later…

The trees remain reddish-brown. There is an estimated 9000 to 93,000 deaths across Europe. And the exclusion zone is still in effect.

The point of the story is:

If ArcGIS was around at the time, they could’ve ran the buffer geoprocessing tool.

Since the blast, satellites like SPOT have been monitoring the Chernobyl exlsuion zone because of its restrictions.

2 The Clip Tool

Bring out the cookie cutter. It’s time to carve out vectors and rasters using the  Clip Tool !

A clip is an overlay tool that cuts out an input layer with the extent of a defined feature boundary. The result of this tool is a new clipped output layer.

Clip Tool
The Clip Tool is a geoprocessing tool that extracts the input feature based on the extent of another polygon feature.

How is the Clip Tool Used in GIS?

  • Add the feature to be clipped.
  • Set the extent to be clipped to using a polygon feature.

The preserved data is defined by the boundary determined in the clip layer.

Clip Tool Example: Carve Out Anything With Your Cookie Cutter

Florida’s nickname is the sunshine state. You can even find the Sunshine State on their license plate.

But how much sunshine does Florida really receive?

We turn to global horizontal irradiance (GHI). What’s GHI? It’s a measure of incoming solar radiation. If you wanted to install a solar panel, GHI is the recommended data set.

Let’s clip GHI to the Florida state boundary to find how much sunshine Florida really gets.

Florida GHI
Global Horizontal Irradiance is clipped to the extent of Florida’s state boundary.

When we clip GHI, we can add it to a map of even summarize the average GHI values.

3 The Merge Tool

What do you do when you have hundreds of data sets, and you want them in a single data set?

You run the  Merge Tool .

The merge geoprocessing tool combines data sets that are the same data type (points, lines or polygons). When you run the merge tool, the resulting data will be merged into one.

Merge Tool
The Merge Tool combines input features from multiple input sources. It creates a single, new, output feature class.

How is the Merge Tool Used in GIS?

  • Add the features to be combined. Make sure they are the same data type.
  • Run the tool. Voila, you have all the features in a single file.

Merge Tool Example: A Supermarket Merger




In the United States, two grocery store giants plan to merge a total of 6,500 stores.

We have two existing data sets – Ahold NV and Delhaize Group grocery stores.

The merger between the two grocery stores into one company – Ahold Delhaize – means all grocery stores will be combined into a single data set.

How would you combine data sets?

You can run the merge tool!

When you combine grocery stores (points) from both companies, they all end up in a final data set.

Question: How is merge different to append?
The append tool means you’re adding data to an existing data set. Merging means you’re taking two existing data sets, combine them together, and create a new merged data set.

4 The Dissolve Tool

The  Dissolve Tool  unifies boundaries based on common attribute values.

How does the Dissolve Tool work in GIS?

The Dissolve Tool merges neighboring boundaries based on common attribute values.

Dissolve Tool
The dissolve tool aggregates neighboring boundaries based on common attribute values.

An example of using the Dissolve Tool is when you dissolve countries to continents. In order to do this, you would need an attribute in each country record. For each country, there must be a continent field indicating the continent it’s in.

Dissolve Tool Example: Unify West and East or Dissolve Countries to Continents

Germany East/West Divide
More than 25 years ago, the Berlin Wall was wiped away which divided East and West. It’s borders were dissolved into a single country.

What do Germany, Yemen, Tanzania and Vietnam all share in common?

They are all examples of two countries dissolving their borders and unifying to form one.

West Germany + East Germany = Germany
North Vietnam + South Vietnam = Vietnam

Country unification is a rare event. But dissolving boundaries in GIS is not.

The dissolve geoprocessing tool erases borders and unifies them into one.

Another example: When each country has its continent name in the attribute table, you can run the dissolve tool to unify borders into continents.

5 The Intersect Tool

The  Intersect Tool  is very similar to the clip tool because the output is defined by the extents of input features.

The only exception is that attributes from all the data sets that overlap each other are preserved in the final data set.

Intersect
The Intersect Tool performs a geometric overlap. All features that overlap in all layers will be part of the output feature class – attributes preserved.

How does the Intersect Tool work in GIS?

  • Add multiple inputs. Different data types (points, lines and polygons) are accepted.
  • When features overlap each other, they will be in the output.

The Intersect Tool preserves the attribute values in both input layers.

Tip of the Day: Run the Intersect Tool on a single feature and you can find overlaps.

Intersect Tool Example: Generating Pivot Tables with Ease

The city councilor asked the GIS analyst: “How many apartments, condos and houses do we have in precinct A, B and C? Create a pivot table for me.”

Instead of running a clip, it would be advantageous to run an intersect. Why? Because we preserve attributes from both input data sets. You need the building type from the dwellings layer. You need the precinct ID from the residential layer.

house count

Here’s how to do it:

  • Add the dwellings and residential layers to the Intersect Tool input.
  • Run the Intersect tool

The output will have all the points that overlap for each precinct. Most importantly, it will keep the dwelling type AND precinct ID.

Select all the rows. Ctrl-C in ArcGIS. Ctrl-V in Excel. Select all. Insert pivot table.

An easier solution: Run the  Tabulate Intersection Tool  in ArcGIS.

What’s the difference between the clip tool and the intersect tool?
The main difference is the resulting attributes. When you run the clip tool, only the input features attributes will be in the output. When you use the intersect tool, the attributes from all features will be in the output.

6 The Union Tool

Some say the Union tool should come with a bottle of antacid. The union tool gets a bad reputation because it creates a lot of features.

After running this geoprocessing tool, it does get a bit messy. But it’s really not so bad.

The Union tool spatially combines two data layers. It preserves features from both layers at the same extents.

Union Tool
The Union Tool maintains all input features boundaries and attributes when it is written to the output feature class.

How does the Union Tool work in GIS?

  • Add features you want to union
  • Run the tool. More records will be generated, especially when there’s more overlaps.

Union Example: Basic Shapes

Here’s a simple example of the Union Tool:

We have an overlapping circle and square. The circle is a single record. The square is a single record.

When you run a union on these two features, it produces 3 records – the original circle, the original square and the overlapping portion.

Unions have been especially useful in animal suitability applications because you can understand where different types of habitats overlap and do not.

7 The Erase (Difference) Tool

I like the erase tool. It’s always been helpful in erasing things!

The input layer is what will be erased. The erase feature determines what will be erased.

Simple as that.

Erase Tool
The Erase Tool removes features that overlap the erase features. This geoprocessing tool maintains portions of input features falling outside the erase features extent.

How does the Erase Tool work in GIS?

  • Add features you want to erase
  • Select the features that you want to erase with.

The result is a new feature with the erase feature extent removed.

Erase Tool Example: Wildfires Tearing Through Forests Calls for the Erase Tool

forest fire

90% of wildfires are started by humans. Lightning strikes the Earth 100,000 times a day. 10 to 20% of these lightning strikes can cause a forest fires.

No matter how you slice it, forest fires are happening all times somewhere on Earth.

Ecologists need to understand how much suitable habitat exists on the landscape.

When a forest fire tears through a forest:

You can run the erase tool because these forest stands no longer exist. They are no longer suitable habitat for certain species.

Erase those areas with the wildfire polygons and BOOM, you have an updated habitat extent.

You’re Ready to Take the Geoprocessing Training Wheels Off

We’ve sifted through the big 7 geoprocessing tools.

These are so common that ArcGIS and QGIS have added them to drop-down menus for easy access.

When you learn these 7 geoprocessing tools, you develop a good baseline of GIS skills.

On top of that, you are one step closer to becoming a GIS guru.

Comments below. Let me know.

See Esri’s Spatial Analysis Map for more real world examples of GIS Processing.

2 Comments on 7 Geoprocessing Tools Every GIS Analyst Should Know

  1. I think your description of Buffer is far too simple and should not be promoted as the first essential tool. It is often used completely inappropriately as you have for Chernobyl.

    All natural buffers are irregular and dependent on other environmental factors. So the fallout around Chernobyl is a plume with a bias downwind, not a perfect circle. Floods follow contours and have surges, not a fixed distance from a centreline or low flow bank. The river surface has a slope not modelled with a buffer. Pollution seeps through the ground depending of the soil and groundwater flows. Even sound has an irregular profile.

    I tell my students ‘Never Use a Buffer” because it is certain to be wrong or at the very best inappropriate. It should be removed from the top of all introductory texts as the essential spatial tool. Just because it looks pretty is not a good reason to use it as an exercise. There are plenty of tools that model spatial influences better than a buffer so we should be careful to teach them from the start.

  2. Agree with “kimo” but it is nonetheless useful in city planning where, for example you have defined an area of maximum commute by a certain residential area to come up with the best location for a school…..but yes there is huge randomness in case of natural “stances” which is absurd to deal with any geometrical buffering…

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