#Topographic Survey
#Topo Map
#basics of surveying

Are you a landowner of a tract of land or a potential buyer of a property you found as viable for some economic purposes you have in mind, but then suddenly you feel uncertain whether that specific industry can cater to the current terrain of the land you are eyeing for? 

Or an architect who was tasked to create an eco-friendly residential design based on the existing terrain conditions of the land your client has just bought in Baguio? But when you went to the site and you tried to capture the existing terrain conditions thru video clips and photos using your smartphone, it appears difficult to proceed with drafting an outstanding design fit for your client?

Or maybe you are a land developer planning to develop that vast area of land, and you have this idea of subdividing a large tract of land into multiple lots? And when the officer from Housing and Land Use Regulatory Board (HLURB) or the Mines and Geosciences Bureau (MGB) or your local zoning officer requested a copy of the Topographic Map, you replied with another question asking what it is for and is it that necessary? 

The officer might have tried to explain something but still, at the end of his detailed explanation with matching hand gestures and probably a sample topo map on hand, all that is clear for you is that you have to look for a Geodetic Engineer asap

Whether you are any of those mentioned or someone who is simply curious and wishes to know more about land surveying products and services, listen, you or someone close to you might benefit from this learning.

What is a Topographic “Topo” Map?

A topographic map is a representation of the earth’s surface in three dimensions. It shows the same features as a planimetric map and in addition indicates relief, usually through contours which are its distinguishing characteristics.1

Elevation contours are imaginary lines connecting points having the same elevation on the surface of the land above or below a reference surface, which usually mean sea level. Contours make it possible to show the height and shape of mountains, the depths of the ocean bottom, and the steepness of slopes. 2

Image 1. 3D view of a certain line (Line 1) vis-à-vis its elevation profile as interpreted in Google Earth. Google Earth (Sep. 28, 2020). 14°26’6.77″N, 121°21’0.72″E. ©2017 Google. http://www.earth.google.com [June 23, 2021].
Image 2. Generated contour lines of the parcel where Line 1 is located.

What are Topo Maps for?

Topo Maps are used to understand the landscape of a certain area mostly for planning and design considerations – be it for Civil Engineering or Architecture Designs, or Mining, or sometimes for recreational uses such as hiking and orienteering.

The preparation of general topographic maps is largely done by agencies of the government.3 In the Philippines, the National Mapping and Resource Information Authority (NAMRIA) is the leading agency responsible for such functions. NAMRIA’s website allows free access to these maps varies, which from a 1:50000 to 1:250,000 scale.

Image 3. A topographic map of Bulan, Sorsogon, in 1:250,000 scale, as downloaded from NAMRIA’s website (Source: https://www.namria.gov.ph/Downloads/topoMap250/bulan.jpg)

For projects which require more specific areas of interest (AOI) however, one can acquire a more detailed topographic map by conducting a more targeted topographic survey over the AOI.

Glimpse on what a Topographic Survey is

A topographic survey gathers data about the natural and man-made features of the land, as well as its terrain. Permanent features such as buildings, fences, trees, and streams accurately define the ground and its boundaries.4 [3]

Image 4. The team, while conducting Topographic Survey using an Electronic Total Station.

How is Topo Map Created?

A topo map can be created using computer software such as AutoCAD Civil3D, ArcGIS, or Surfer. Spatial data obtained from field surveys are imported into the software which can automatically generate contours. Depending on the needs of the project, one can set the contour interval (index) to 1m, 2m, or even up to 5m or greater.

Image 5. Generated Contours using ©AutoCAD Civil 3D 2022.

Depending on the area or extent of the project and the required accuracy, our team can offer ways of how to maximize your budget based on your timeline.

To discuss your project with us and to find out more if it could benefit from a topographic survey, email us at lph.lphlandsurveyingservices@gmail.com.

1Juny Pilapil La Putt, Higher Surveying, 2008 Reprint Version, page 84.
2USGS, What is a topographic Map, available at https://www.usgs.gov/faqs/what-a-topographic-map?qt-news_science_products=0#qt-news_science_products (last accessed June 23, 2021).
3Juny Pilapil La Putt, Higher Surveying, 2008 Reprint Version, page 84.
4John MacIntyre, Everything You Need to Know About Topographic Surveys, available at https://www.technicsgroup.com/2019/05/everything-you-need-to-know-about-topographic-surveys/ (last accessed on June 21, 2021).

Leave a Reply

Your email address will not be published. Required fields are marked *