Mermaid diagram editor

1. What is Mermaid?

Mermaid is a simple markdown-like language you can use to create diagrams and flowcharts from text.

It’s perfect for GIS analysis workflows because you can easily sketch processes like:

• Data collection
• Data preprocessing
• Spatial analysis
• Visualization
• Reporting

👉 You write text → Mermaid renders diagrams.

You can use Mermaid in:

• Markdown editors (like Obsidian, Typora)

• GitHub markdown

• Websites (with Mermaid.js)

• Tools like Mermaid Live Editor

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2. Basic Syntax for Flowcharts

A simple flowchart in Mermaid uses flowchart keyword.

flowchart TD
  id1[/Start/] --> B[Load Spatial Data]
  B --> C{Is the data clean?}
  C -- Yes --> D[Proceed to Analysis]
  C -- No --> E[Preprocess Data]
  E --> D
  D --> F[Perform GIS Analysis]
  F --> G[Create Maps and Reports]
  G --> H[End]

• TD = Top Down (flow vertically)

• --> = arrow

• {} = decision/condition node

• [] = regular step/action

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3. Example: Typical GIS Analysis Flow

Imagine a GIS analysis where you:

• Download a shapefile

• Validate geometries

• Reproject

• Perform an overlay analysis

• Make a map

Here’s a Mermaid diagram for that: flowchart TD

A[Download Shapefiles] --> B[Validate Geometries]
B --> C{Valid?}
C -- No --> D[Fix Geometry Errors]
C -- Yes --> E[Reproject to Target CRS]
D --> E
E --> F[Overlay Analysis (Intersect, Union)]
F --> G[Calculate Statistics]
G --> H[Symbolize Results in Map]
H --> I[Export Map and Data]

flowchart TD
	A[Download Shapefiles] --> B[Validate Geometries]
    B --> C{Valid?}
    C -- No --> D[Fix Geometry Errors]
    C -- Yes --> E[Reproject to Target CRS]
    D --> E
    E --> F[Overlay Analysis 'Intersect, Union']
    F --> G[Calculate Statistics]
    G --> H[Symbolize Results in Map]
    H --> I[Export Map and Data]
    

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4. Some Tips for GIS Flows

• Use decisions {} to model “if-else” situations (e.g., data valid or not).

• Group things using subgraphs if you want (e.g., “Preprocessing”).

Example:

flowchart TD
    subgraph Preprocessing
      A1[Download Data] --> A2[Validate Geometries]
      A2 --> A3[Reproject]
    end

    subgraph Analysis
      B1[Buffer Features] --> B2[Spatial Join]
    end

    A3 --> B1
    B2 --> C[Create Map]

• Use different directions:

  • TD = top-down

  • LR = left-right

  • BT = bottom-top

Example:

flowchart LR
    Start --> LoadData --> CleanData --> Analyze --> Map --> End

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5. Common GIS Analysis Elements You Might Use

Mermaid Shape	Use Case in GIS
[Text]	Standard process step (e.g., “Reproject Data”)
{Question?}	Decision point (e.g., “Valid Data?“)
((Circle))	Special action like “Start” or “End”
>Text] or [Text<	Inputs/Outputs

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6. Tools to Use Mermaid

• Mermaid Live Editor (online)
• Obsidian (markdown + diagrams)
• GitHub markdown
• Jupyter notebooks (with Mermaid plugin)

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🎯 Summary: How to Start

1. Think through the GIS analysis steps you want to visualize.
2. Go to Mermaid Live Editor (online)
3. Start a Mermaid flowchart TD block.
4. Use arrows --> to show steps and decisions {} for checks.
5. Render it in a Mermaid-supported environment.