Summary of "Konversi DSM to DTM dengan PCI Geomatics"

Summary

The video is an instructional guide on converting Digital Surface Models (DSM) to Digital Terrain Models (DTM) using PCI Geomatics software. It is aimed at students participating in digital photogrammetry practical classes.

Key Technological Concepts and Definitions

Digital Elevation Model (DEM): A general term representing earth surface elevation.
Digital Surface Model (DSM): Elevation model including surface objects such as buildings, trees, and vegetation.
Digital Terrain Model (DTM): Elevation model representing the bare earth surface with buildings and vegetation removed.
Orthophoto (DOM): Aerial photo corrected for relief displacement using DSM, showing true ground positions.

Important Clarifications

There are two schools of thought regarding DEM and DTM terminology:

Some consider DEM and DTM to be the same.
Others view DEM as the broad category, with DSM and DTM as subtypes.

The instructor follows the latter approach, treating DEM as the umbrella term.

Practical Application

DSM is used in orthophoto production because it retains building and vegetation heights necessary to correct relief displacement errors.
DTM is not used for orthophoto production but is an important secondary output for understanding terrain features and surface conditions.
Photogrammetry projects often require both DSM (for orthophotos) and DTM (for terrain analysis).

PCI Geomatics Software Tutorial

The video demonstrates a manual method to convert DSM to DTM after an automatic method attempt failed.

Steps:

Open PCI Geomatics Focus and load DSM data (PCDK format).
Use the Layer menu to access DEM Editing.
Digitize a polygon defining the work area boundary.
Apply filters sequentially:
- Trend filter (flat): Smooths flat urban areas.
- Remove Bum: Removes bumps or elevated anomalies.
- Remove Pit: Fills holes or depressions.
- Median filter: Smooths edges such as hill or road boundaries.
- Clam filter: Stabilizes pixel values.
Adjust filter parameters:
- Size: Controls the maximum pixel size of objects to be removed (larger size removes bigger objects).
- Gradient: Controls slope threshold for removal (e.g., slopes above 30 degrees are removed).
Filters can be applied iteratively to refine results.
Polygons for filters can be:
- Global: Cover the entire area.
- Local: Focus on smaller, specific areas.
Backup DSM files before applying filters to avoid accidental overwrites.

Reporting and Documentation

Students should document the following:

Original DSM screenshot.
Filter parameters used (size, gradient).
Order of filters applied and reasons for their use.
Results after each filter application.
Comparison between the original DSM and the final DTM.

Summary Remarks

The process is straightforward and takes about 30 minutes.
The video serves as an asynchronous substitute for offline classes.
Students are encouraged to follow assistants’ guidance during lab sessions.

Main Speaker and Support

The instructor (unnamed) delivers the practical tutorial.
Assistants “Mas Niko” and “Mbak Farin” support the practical classes.

Overall, the video serves as a concise tutorial and explanation on DSM to DTM conversion using PCI Geomatics, clarifying conceptual differences and providing hands-on procedural guidance.