This is part three of a three-part tutorial that introduces the basics of digitally drafting an underwater cave map using Adobe Illustrator. To start at part one, click here.

Introduction

This tutorial shows how to draft cross-sections for an underwater cave map using Adobe Illustrator. For this specific project, the cross-sections will be drawn to 2x the scale of the plan view.

The process will be very similar to the drafting method used for the walls and columns in part one of this series, with the main difference being that the cross-sections are done in a separate layer.

I want to reiterate that this series is a simplified demo for divers interested in cartography. It is not meant to be a complete Adobe Illustrator tutorial as there are already several excellent free tutorials online.

In future tutorials, we will go into greater detail, particularly with managing and exporting the survey data, and I think you will better understand those procedures by having done this short project first.

What do I need for the tutorial?

• Adobe Illustrator, free trial here.

• Desktop or laptop, preferably with a mouse.

• The completed tutorial file from Part 2.

• The tutorial file:

Quick facts

If you are already familiar with Illustrator, download the tutorial file and Place the cross-sections scan into the Scans layer. Hide the Details layer and line up the survey of the new scan with the survey of the Illustrator file. You may have to slightly resize and rotate the image. Un-hide the details layer once the scan is aligned.

Working in the w2d Walls sym sub-layer, trace the cross-sections with a Stroke of 0.5 pt and use the Line Segment Tool (\) to draw the section lines leading back to the plan view. Two arrow symbols are included in the PDF within the tutorial file which can be used as symbols for the directional arrows.

Apply a color fill to the cross-sections by selecting the drawing and double-clicking the Fill color box. Cross-section colors do not need to follow the procedure used in Part 2 as they are not reshaped like walls when roundtripping – this is also the reason cross-sections are drawn in a different layer.

Illustrator Tutorial:
TRACING CROSS-SECTIONS

• by Rory O’Keefe, November 28, 2020

Introducing one new tool

One additional tool will be used to trace the section lines which show the section of cave that the cross-sections were drawn from.

Line Segment Tool (shortcut, \):

• A simple tool to draw straight lines.

• Click and drag on the artboard from the point you want to draw a line.

• Hold shift while drawing a line to lock the line at 0 degrees or increments of 45 degrees.

Tracing cross-sections

Step 1: Import the new scan.

• Open the completed tutorial file from Part 2.

• Navigate to and unlock the Scans layer then go to File > Place and select the scanned image, Cross-Sections – August 14, 2020.

• The scan may need to be aligned. To do this, hide the w2d Details layer for easier viewing of the scan, and position it so that the survey of the image aligns with the survey of the Illustrator file. You may need to slightly rotate and resize the image for a perfect fit.

• Note: As mentioned in Part 1, the Illustrator file survey differs slightly from the scanned survey along the outer sections as the data has been updated since the scan was made. This error is corrected on the actual map but for the purpose of this tutorial, focus on aligning the middle sections of the two surveys.

• When the scan is aligned, lock the Scans layer and unhide the w2d Details layer.

Step 2: Trace.

• The cross-sections will be traced in the w2d Walls sym sub-layer so that they are not reshaped with the walls during roundtripping. To work on the w2d Walls sym sub-layer, unlock Layer 1, w2d Walls, and w2d Walls sym.

• Use the Pencil Tool (N) to trace the cross-sections using the same process used to trace the walls in Part 1, then apply a Stroke of 0.5 pt.

• I draw speleothems as part of the floor and ceiling lines rather than separate objects. This is a personal preference so feel free to draw speleothems separately if you would prefer to add more color.

Step 3: Add color.

• Add color to the cross-sections by selecting them with the Direct Selection Tool (V).

• Next, double-click the Fill color block under the Tools Panel.

• The Color Picker window will appear – use this to select the same color used to represent water on the plan view. I used color # AEE0F4.

Step 4: Add section lines and directional arrows.

• The directional arrow indicates from which direction facing into the cave that the cross-section was drawn.

• Open the PDF file, Directional Arrows, in Illustrator. Copy and paste the arrows into your map file and roughly position them over the directional arrows in the scan.

• Use the Line Segment Tool (\) to draw a line across the passage which follows the angle between the directional arrow and the section line.

• Add a directional arrow over the scanned arrow and rotate it so that it follows the same angle as the line you drew above.

• Add the horizontal section lines as shown in the scan, at the floor level of the cave on both sides of the cross-section.

• Use the Scissors Tool (C) to cut the angled section line outside of the passage walls, and delete the half which cuts across the map.

• Select all of the section lines using the Direct Selection Tool (V) and apply a Stroke of 0.5 pt in the Properties Panel.

• Note: The length of the section lines can be changed from what is drawn in the scan based on the layout of the final map.

Step 5: Clean up.

• Lock all of the layers and hide the Scans layer by selecting the Eye icon to the left of the layer title.

Step 6: Save your work!

• Save the updated Illustrator file.

• To save a print file, go to File > Save As... > Adobe PDF and select the Adobe Preset: High Quality Print.

The end of part three

If you’d like to continue playing around with the map, you can try the following:

• Add/create symbols in the w2d Detail sym sub-layer to show floor-to-ceiling heights, depth, restrictions, etc.

• Add your name, cave statistics, etc to the w2d Legend layer.