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How to Use Deneb in Power BI

Cody Schneider••9 min read

Ready to create dazzling, custom visualizations in Power BI that leave the standard charts in the dust? If you've ever felt constrained by the built-in options and wished for more creative freedom, it's time to meet your new best friend: Deneb. This article will show you exactly how to get started with Deneb and build your first custom chart, step by step.

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What Is Deneb, Anyway?

Deneb isn't just another chart type. It’s a custom Power BI visual that serves as a canvas for the Vega and Vega-Lite grammar of graphics. Think of it this way: Power BI's standard visuals are like pre-built Lego sets. They're useful and easy to assemble, but you can only build what's pictured on the box. Deneb, on the other hand, is like getting an infinite bucket of every Lego brick imaginable - you have the complete freedom to build anything you can design.

This "grammar of graphics" approach means you describe how your data maps to a visual representation using simple, declarative language. This unlocks a new level of flexibility to create visuals that would be difficult or impossible otherwise, such as:

  • Connected scatterplots
  • Advanced small multiples (trellis charts)
  • Custom-styled funnel or pyramid charts
  • Industry-specific visuals like slope graphs or Sankey diagrams

For this tutorial, we will focus on Vega-Lite, a high-level, introductory version of Vega that is more than powerful enough for most custom charting needs and much easier for beginners to grasp.

Step 1: Get Deneb in Your Power BI Report

First things first, you need to add the Deneb custom visual to your Power BI palette. The process is simple and takes less than a minute. You only need to do this once, and it will be available for all your future reports.

  1. Open a Power BI Desktop file. In the Visualizations pane on the right, click the three dots (...) icon to "Get more visuals."
  2. This will open the Power BI Visuals marketplace (AppSource). Use the search bar to look for "Deneb."
  3. Find the Deneb visual and click the Add button. Power BI will confirm that the visual has been imported successfully.
  4. You'll now see the Deneb icon (it looks like the Ursa Minor star constellation) at the bottom of your Visualizations pane.
  5. Click this new icon to add a Deneb visual template to your report canvas. It will appear as a blank placeholder, ready for you to get to work.

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Step 2: Building Your First Deneb Chart - A Simple Bar Chart

With an empty Deneb visual on your report canvas, you'll see a landing page guiding you to "Create a new Deneb/Vega-Lite specification." Click this to open the Visual Editor, which is where the magic happens.

The editor has two main sections:

  • The left side is a text editor where you'll write or paste your Vega-Lite code (called a "specification" or "spec").
  • The right side provides a live preview of how your visualization looks as you build it. Don't worry, you won't break anything!

Data Preparation: Getting Data Into Deneb

Before writing any code, we need to give Deneb access to our data. This works just like any other Power BI visual. For this example, let's assume we have a simple dataset with two fields: Category for our product types and Sales for our revenue.

  1. Select the Deneb visual on your canvas.
  2. From your Fields pane, drag your Category and Sales fields into the Values bucket in the Visualizations pane.

That's it! Now the data is available for Deneb to use. The visual itself will still look blank until we create a spec that tells it what to do with that data.

Writing Your First Vega-Lite Spec

Vega-Lite specs are written in a structured format called JSON (JavaScript Object Notation). It might look intimidating at first, but once you understand the core components, it's quite logical. Every simple Vega-Lite spec needs to define these key elements:

  • data: Tell it where to find the data. In our case, it's the dataset from Power BI.
  • mark: Tell it what shape to draw (a bar, a line, a circle, etc.).
  • encoding: The most important part. This is where you map your data fields to the visual properties (like the x-axis, y-axis, and color).

Let's build a classic bar chart. In the left-hand text editor within Deneb's visual editor, copy and paste the following code:

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "data": {"name": "dataset"},
  "mark": "bar",
  "encoding": {
    "x": {"field": "Category", "type": "nominal"},
    "y": {"field": "Sales", "type": "quantitative"}
  }
}

Once you click "Apply" (the little play button), you should see a bar chart magically appear in the preview pane!

Let's Break Down That Code

  • "$schema": "https://vega.github.io/schema/vega-lite/v5.json": This line provides schema validation and enables helpful auto-complete features. It's good practice to keep it.
  • "data": {"name": "dataset"}: This is the crucial link. It tells Vega-Lite to use the data we dragged into the "Values" well in Power BI.
  • "mark": "bar": This one is straightforward - we’re telling it to draw bars. You could change this to "line", "point", or "arc" to get different chart types.
  • "encoding": { ... }: This section is the core of the chart. It's the set of mapping rules, a.k.a. the "encoding channels."
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Step 3: Leveling Up Your Chart

A basic bar chart is great, but the real power of Deneb lies in its customization. Let's add color, custom tooltips, and cleaner axis titles to make our visual more informative and polished.

Adding Dynamic Color Based on Your Data

To really make the categories an insightful part of this visualization, we'll try coloring each bar differently based on its category. This is as simple as adding a color channel to our encoding section. Update your code to look like this:

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "data": {"name": "dataset"},
  "mark": "bar",
  "encoding": {
    "x": {"field": "Category", "type": "nominal"},
    "y": {"field": "Sales", "type": "quantitative"},
    "color": {"field": "Category", "type": "nominal"}
  }
}

By adding that single color line, we’ve instructed Deneb to use the same Category field to both position the bars and to assign a unique color to each of them.

Adding Interactive Tooltips and Formatting

Right now, if you hover over a bar, nothing happens. A good chart should reward curiosity! Let's add tooltips that display the exact category name and sales numbers when a user hovers over a bar. We can even format the sales number with a dollar sign and commas.

Here’s the updated spec, which is a bit more robust:

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "description": "A customized bar chart showing total sales by product category.",
  "data": {"name": "dataset"},
  "mark": {
    "type": "bar",
    "tooltip": true
  },
  "encoding": {
    "x": {
      "field": "Category", 
      "type": "nominal",
      "title": "Product Category"
    },
    "y": {
      "field": "Sales", 
      "type": "quantitative",
      "title": "Total Sales Revenue"
    },
    "color": {
      "field": "Category", 
      "type": "nominal",
      "legend": null
    },
    "tooltip": [
      {"field": "Category", "title": "Category"},
      {"field": "Sales", "title": "Sales", "format": "$,.2f"}
    ]
  }
}

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Decoding the New Additions:

  • "mark": {"type": "bar", "tooltip": true}: We simply modified "mark" into a more detailed object to add more properties - in this case, enabling the tooltip functionality.
  • "title": "Product Category", "title": "Total Sales Revenue": An easy, yet powerful change. In both the x and y encoding properties, we added a title property to provide a cleaner, more human-readable label for our axes.
  • "legend": null: Since each bar's label and color represent the same thing, the default color legend is redundant. This line hides it to declutter our visual.
  • "tooltip": [ ... ]: Instead of one single "tooltip" encoding, we're now including both fields in our tooltip functionality as well. Most importantly, look at the Sales entry!
  • "format": "$,.2f": This is where we control the number format for our tooltip. This specific syntax translates to: show a dollar sign ($), use comma separators for thousands (,), and include two decimal points (.2f). This little detail makes your visual feel much more professional.

Finding Inspiration and Getting Help

As you move beyond basic charts, you don't have to start from scratch. The data visualization community is incredibly generous, and there are amazing resources at your disposal.

  • Vega-Lite Examples Gallery: This should be your first visit when you are ready to build a different type of visual. It's a massive and filterable collection of chart types with their full Vega-Lite code available for you to adapt. Find something you like, copy the code into Deneb, and start linking it to your Power BI data one piece at a time. It might feel daunting at first, but breaking the big code into bite-sized chunks helps!
  • Deneb's official documentation and guides: The visual editor also provides ready-to-use templates as well as guided tours and examples if that works better for you.
  • Use the Community for feedback and collaboration: There are numerous resources where members are more than willing to answer questions and share examples.

Final Thoughts

Deneb unlocks incredible creative potential within Power BI, empowering you to move beyond pre-defined visuals and craft the exact charts your data story needs. While getting started with JSON specs may seem intimidating, beginning with a simple chart and incrementally adding customizations like tooltips and color is a friendly way to learn the syntax and understand the power at your fingertips.

But building highly custom visuals can take time, especially when you are just starting or only have a quick question. We built Graphed for the moments you need an answer, fast. Once you connect marketing and sales sources like Google Analytics, Shopify, or Salesforce, you can skip the process of writing code or manually finding the correct chart in the library completely. You can just ask a question in plain English like, "What were our total sales by product category last month?" - and Graphed instantly builds the live, interactive visualization for you, helping you get the answers you want on demand. This allows you to build them faster into your executive dashboards later on.

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