GIS Experience with JPS Selangor
This section is meant to showcase my internship work as a GIS Assistant Analyst at JPS Selangor, Shah Alam. This environment was typically filled with engineers and Quantity Surveyors who were engaged in construction and consultancy projects, which I found to be very exciting. During that time, the Deputy Director, Ir Hj Mohd Nazri, guided me extensively on the application of GIS in JPS projects, primarily for testing, analyzing, and presenting.
Extracting Contour Lines and DEM from Google Earth for Visualization in ArcMap: Ulu Yam Project
Outline of Catchment using Google Earth Pro
The project site is located at coordinates 3°26'47.66"N (latitude), 101°37'38.63"E (longitude) in the Hulu Langat district. This area features a tributary stream (Anak Sungai Liam) that flows into a major river (Sungai Liam), which eventually joins the main river (Sungai Selangor). The project plan includes a residential area situated to the west in relation to the project area.
Outlining the catchment for elevation analysis.
The digitization method utilizes the line path tool to obtain elevation information along the project area. Once the entire area is digitized, the data will be saved in KML/KMZ file format. This method aids the digitizer in processing the elevation information into ArcGIS software later on.
Data converting from KMZ to GPX file
The saved KMZ/KML data files are being processed into GPX files on gpsvisualizer.com. This metadata conversion ensures compatibility with ArcGIS software. This website's format conversion functions are valuable for GIS professionals dealing with different software. I used it to convert KMZ to GPX (GPS) files, as ArcGIS offers tools to convert GPX data to features.
Result converting & presenting in ArcGIS
The GPX files will be processed in ArcMap using the "Conversion Tools: GPX to Features" toolbox in ArcGIS. This will yield 2D project area data represented as elevation-inclusive points. These points derive elevation metadata from a basic terrain portrayal on Google Earth Pro using DEM data sourced from LiDAR technology. DEM data helps identify varying ground elevations effectively.
Data processing into IDW data
DEM features will undergo IDW interpolation using the Geostatistical Analyst Tool, specifically Interpolation Inverse Distance Weighted (IDW). IDW involves deterministic interpolation based on weighted average values around scattered points. The outcome shows color variation reflecting the project area's elevation. Dark green represents higher areas, while brighter colors indicate lower elevations.
IDW, River & Contour Layer Map
Contour lines can be generated after obtaining the IDW data. The contour line processing method involves the use of the Spatial Analyst Tools; Surface tool. Contour data is crucial for obtaining a clearer depiction of boundaries, elevations, and widths within an area. The outcome serves as a reference for relevant parties in determining river flow directions, water catchment areas, and more.
Layering and masking with working area
The image above (click for full view) depicts contour lines overlaid with the Ulu Yam catchment line and Sungai Selangor data, representing the final outcome of the task. The river flowing within the water catchment area is the Anak Sungai Liam, originating from an elevation of 90 meters (yellow line) and flowing into Sungai Liam in the Hulu Langat district. This data is highly beneficial for contractors, geographers, engineers, and others to analyze elevations and strategize construction plans within the Ulu Yam water catchment area.
Basic Drone Training with JPS & DJI
Drone Phantom 4 Pro V2.0
Utilized by GIS and Design Unit, the Phantom 4 Pro V2.0 drone captures 4K/60fps videos and 2MP images with its 1-inch CMOS sensor. Its OcuSync 2.0 HD system ensures stable connection, high safety reliability, and 5-directional obstacle sensing. It includes a small screen on the remote controller for precise control.
Training with DJI team
Mr. Din, the DJI moderator, introduced the OcuSync 2.0 system and highlighted the use of drone technology in mapping and videography. He discussed various drone models including Flame Wheel, Phantom, Mavic, Spreading Wings, Inspire, Matrice, Spark, and FPV. The differentiation in drone types is based on their intended purposes.
Kuala Perlis Drone Mission
Displaying a rough collection of aerial images of Kuala Perlis captured by the Phantom 4 Pro V2.0 drone. These images were taken using the drone's automated "Mission" system to capture visuals along a predefined path. In total, 166 images were captured, which will be compiled using Pix4DMapper software.
Mission path & Pix4DMapper Application
The images show the drone's mission path for aerial capture over Kuala Perlis. They are automatically processed in Pix4DMapper software. The ortho image generation involves three main steps, with Initial Processing allowing users to balance quality and speed. This step produces orthomosaic images and Digital Surface Model (DSM) data for the Quality Report.
Orthomosaic & DSM data
The report regarding orthomosaic and DSM will be generated by the system, presenting relevant information about the project area. This facilitates analysis and provides a clearer understanding of the area's attributes. It also offers an initial overview of the elevation in different parts of the area.
Densified Point Cloud or Densification.
The second process is the densification process or densified point cloud (DPC), which involves a set of points forming a 3D model. The X, Y, Z positions, and color arrangement are determined and stored within each point during the densified point cloud process. The DPC process generates an accurate background in terms of distance, surface, and volume measurements of the project area. This step also performs the 3D Textured Mesh process to create a clearer and accurate 3D model image through the compilation of triangular shapes.
Digital Surface Model (DSM) - last stage
The final stage in processing drone images includes DSM, Orthomosaic, and Index data, as outlined above. The Light Detection and Ranging (LiDAR) system is a technology that emits light onto the ground and captures the reflected signal to obtain a series of distance or elevation measurements of the Earth's surface. LiDAR generates a point cloud dataset containing elevation values.