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newSchoolWorks.com › VoTechWorks › Technology & Design › GIS / Surveying / Drone Operations › Photogrammetry: Aerial and Close-Range Measurement › Lesson 9
TEC-GIS45-06 · Lesson 9 · 14 clock hours · lab

Integrating Photogrammetric Products in ArcGIS Pro

Objective. Students import orthomosaic and DEM products into ArcGIS Pro, generate contours and slope layers, extract planimetric features by heads-up digitizing, and symbolize results for a professional map layout.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by an industry-certified professional or by a certification or approval body. It is a study draft and may contain errors. Do not use it as instructions for work on a job site or on live equipment. Always follow your instructor, your supervising professional, and current official references and regulations.

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Integrating Photogrammetric Products in ArcGIS Pro

Once your photogrammetry software has produced an orthomosaic and a digital elevation model (DEM), those products become raw material for mapping and analysis. ArcGIS Pro is the industry-standard desktop GIS platform used to turn those raster outputs into finished, professional deliverables. This lesson walks you through the full workflow: data import, coordinate system verification, contour and slope generation, heads-up digitizing, and map layout export.

Loading Data and Setting the Coordinate Reference System

Open a new ArcGIS Pro project and add your orthomosaic and DEM using the Add Data button or the Catalog pane. Before any analysis, confirm that both rasters share the same projected coordinate reference system (CRS). A geographic coordinate system (latitude/longitude) is not appropriate for planimetric measurement because its units are degrees, not meters or feet. For most US survey work, a State Plane or UTM zone in NAD 83 is standard.

To check or assign a CRS, right-click the layer → Properties → Source. If the raster was exported from your photogrammetry software with the correct CRS embedded, ArcGIS Pro will read it automatically. If the CRS is missing or wrong, use Project Raster (Data Management toolbox) to reproject — do not simply use Define Projection, which only labels the data without transforming it. Mismatched CRS between the orthomosaic and DEM will cause spatial misalignment and invalidate every measurement you make afterward.

Generating Contours and Slope

Contours are lines of equal elevation derived from the DEM. In the Spatial Analyst toolbox, navigate to Surface → Contour. Set the contour interval to 0.5 m as required for this project. After the tool runs, visually compare the contour lines to the DEM hillshade: contours should follow terrain logically, close on themselves on hills and depressions, and never cross. Watch for these common artifacts:

If you spot artifacts, report them in your accuracy note — do not edit contours manually to hide a data problem.

The Slope tool (Spatial Analyst → Surface → Slope) computes the rate of elevation change for each raster cell, expressed in degrees or percent rise. A slope layer is useful for drainage analysis and site planning and complements the contour map.

Heads-Up Digitizing

Heads-up digitizing means drawing vector features on screen while using the orthomosaic as a visual backdrop — the same principle as tracing on a light table, but digital. You will create three feature classes in a file geodatabase:

1. Edge of pavement (polyline)

2. Building footprints (polygon)

3. Drainage features (polyline or polygon, per the feature-code list)

Create each feature class with New → Feature Class in the Catalog pane, choosing the correct geometry type and assigning the same CRS as your rasters. Add a text field named FEAT_CODE and populate it using the provided feature-code list for every feature you digitize.

Digitizing tips:

Accuracy depends on the ground sample distance (GSD) of your orthomosaic. A 3 cm GSD orthomosaic supports digitizing to roughly ±5–10 cm on the ground.

Map Layout Assembly

A professional map layout communicates your results clearly to someone who was not involved in the field work. In ArcGIS Pro, switch from Map view to Layout view using the Insert → New Layout menu. Required cartographic elements:

| Element | Notes |

|---|---|

| Title | Descriptive, includes project area and date |

| North arrow | Oriented to true or grid north; state which |

| Scale bar | In the same units as your CRS (meters or feet) |

| Legend | All symbolized layers labeled clearly |

| Coordinate grid | Graticule or grid matching your CRS |

| Accuracy note | States contour interval, source data GSD, datum, and any known artifacts |

Use the provided map layout template so that margins, fonts, and logo placement meet program standards. Export to PDF at 300 dpi minimum using Share → Export Layout.

Safety and Data Integrity Notes

No physical hazards exist at the GIS workstation, but data integrity is the professional equivalent of safety in this discipline. Save your project frequently (Ctrl+S). Keep original raster files read-only so no tool accidentally overwrites source data. Store all outputs in a dedicated folder inside your project geodatabase, not on the desktop. Back up your project to the class network drive before submitting. A corrupt or missing project file cannot be graded and may not be recoverable.

Key terms9

OrthomosaicA georeferenced, orthorectified image mosaic produced from overlapping aerial photographs; each pixel represents a true planimetric position on the ground.
Digital Elevation Model (DEM)A raster grid in which each cell stores the elevation of the ground surface at that location, used as the source for contour and slope generation.
Coordinate Reference System (CRS)The mathematical framework — including datum, projection, and units — that ties raster and vector data to real-world geographic positions.
Contour IntervalThe constant difference in elevation between successive contour lines; in this project, set to 0.5 m.
Heads-Up DigitizingThe process of drawing vector features on screen by tracing visible detail on a raster backdrop such as an orthomosaic.
Feature Code (FEAT_CODE)A standardized alphanumeric identifier assigned to each digitized feature to indicate its type, enabling consistent attribution and later data exchange.
Ground Sample Distance (GSD)The real-world size represented by one pixel of an aerial image or orthomosaic; smaller GSD means finer detail and supports higher digitizing accuracy.
Map LayoutIn ArcGIS Pro, a composed page that combines map frames, title, legend, scale bar, north arrow, and other cartographic elements for print or PDF export.
Slope RasterA derived raster in which each cell value represents the rate and direction of elevation change, expressed in degrees or percent rise.

Worked examples4

1. The DEM has a cell size of 0.05 m. You need to confirm that your 0.5-m contour interval is at least 10 times the cell size — a rule of thumb that ensures contours are meaningful rather than following cell-to-cell noise. Does 0.5 m satisfy this check?
  1. Identify the DEM cell size: 0.05 m.
  2. Multiply cell size by 10: 0.05 m × 10 = 0.50 m.
  3. Compare to the required contour interval: 0.50 m ≥ 0.50 m.
  4. The interval exactly meets the minimum threshold, so it is acceptable.
Answer: Yes. A 0.5-m contour interval is exactly 10 times the 0.05-m cell size, satisfying the rule of thumb. The contours are meaningful for this DEM.
2. Your orthomosaic has a GSD of 3 cm. The map will be plotted at 1:1,000 scale. What is the map-sheet distance (in mm) that represents a 1-m ground distance?
  1. Recall the scale relationship: map distance = ground distance ÷ scale denominator.
  2. Convert 1 m to mm: 1 m = 1,000 mm.
  3. Divide by the scale denominator: 1,000 mm ÷ 1,000 = 1.0 mm.
  4. So 1 m on the ground equals 1.0 mm on the plotted map.
Answer: 1.0 mm on the map represents 1 m on the ground at a scale of 1:1,000.
3. A slope raster cell shows an elevation difference of 2.4 m over a horizontal distance of 6.0 m. Calculate the slope in percent rise.
  1. Recall the formula: slope (%) = (vertical rise ÷ horizontal run) × 100.
  2. Substitute values: (2.4 m ÷ 6.0 m) × 100.
  3. Divide: 2.4 ÷ 6.0 = 0.40.
  4. Multiply by 100: 0.40 × 100 = 40%.
Answer: The slope is 40 percent rise.
4. You digitize a rectangular building footprint with corners at coordinates (in meters): (100, 200), (130, 200), (130, 250), (100, 250). What is the footprint area in square meters?
  1. Calculate the width: 130 m − 100 m = 30 m.
  2. Calculate the length: 250 m − 200 m = 50 m.
  3. Multiply width × length: 30 m × 50 m = 1,500 m².
  4. Confirm units: both dimensions are in meters, so area is in square meters.
Answer: The building footprint area is 1,500 m².

The math in this lesson1

Learners check a 0.5 m contour interval against 10 times a 0.05 m DEM cell size.
N-Q.3
Brush up in the math halls at newSchoolWorks.com:
In class: Data integration: students load the Lesson 7 orthomosaic and DEM into a new ArcGIS Pro project, set the correct coordinate reference system, and use the Contour tool to generate 0.5-m interval contours, inspecting them against the DEM for artifacts. · Heads-up digitizing: using the orthomosaic as a backdrop, students digitize a set of assigned planimetric features (edge of pavement, building footprints, drainage features) as polygon and polyline feature classes, attributing each with a feature code. · Map layout assembly: students create a print-ready map layout in ArcGIS Pro including title, north arrow, scale bar, legend, coordinate grid, and accuracy note, then export to PDF and submit alongside the ArcGIS Pro project file.
Materials: ArcGIS Pro (licensed workstations), processed orthomosaic and DEM, Esri ArcGIS Pro documentation, map layout template, digitizing feature-code list
Check: Instructor reviews the PDF map layout and ArcGIS Pro project; contour interval must be correct; digitized features must be attributed; layout must contain all required cartographic elements; pass = all elements present and spatially accurate per instructor rubric.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

Esri ArcGIS Pro — Raster data management
1. A student imports an orthomosaic into ArcGIS Pro and notices the raster has no coordinate reference system assigned. Which tool should be used to assign the correct CRS AND mathematically transform the data to the new coordinate system?
Esri ArcGIS Pro — Surface analysis
2. When generating contours in ArcGIS Pro with the Spatial Analyst Contour tool, what input dataset is required?
Photogrammetry — DEM quality inspection
3. After running the Contour tool at a 0.5-m interval, you notice several contour lines crossing each other in a low-lying area. What is the most likely cause?
Esri ArcGIS Pro — Vector data creation
4. Which of the following is the correct geometry type to use when creating a feature class for building footprints during heads-up digitizing?
Esri ArcGIS Pro — Digitizing best practices
5. A student is digitizing edge-of-pavement lines at a zoom level of 1:5,000. The orthomosaic GSD is 3 cm. What is the most appropriate action to improve digitizing accuracy?
Esri ArcGIS Pro — Cartographic layout
6. Which required map layout element tells the map reader the relationship between a distance measured on the printed map and the corresponding distance on the ground?
Photogrammetry — Surface analysis calculation
7. A DEM cell records a horizontal run of 4.0 m and a vertical rise of 1.0 m. What is the slope expressed in percent rise?
Esri ArcGIS Pro — Cartographic standards / NSPS survey documentation
8. The accuracy note on a finished map layout must include which of the following items to meet the requirements of this project?
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