Terrain an Imagery Manual

Table of Contents

  • Intro
  • Data Sources
  • Elevation Data
  • LiDAR Data
  • The National Map
  • GeoComm
  • Imagery
  • SAS.Planet
  • Map APIs
  • Global Mapper
  • GIS Mapping Software
  • Global Mapper
  • Projection
  • Unknown Source Projection
  • Rectifying
  • Rectifying a DXF Mesh
  • Manual Adjustments to a Projection
  • Projection Parameters
  • Coordinate Transformation Shift
  • Measuring an Offset Adjustment
  • Coordinates
  • 3DEM
  • Golf Architect Software
  • Red Chain (CPG / WGC / Simulators)
  • Headgate (PGA 2000 / Tiger Woods Series)

Introduction

Imagery and Elevation Data

This manual details usingelevation data and imagery in creating digital models of golf courses playable on computers and simulators. The primary focus is to maximize accuracy in a relatively simple, repeatable process.

There are three major parts to the process.

  • Data Sources - Finding and downloading data.
  • GIS Mapping Software - Working with data in mapping software known as Geographic Information System (GIS) software.
  • Golf Architect Software - Importing data into specialized golf architect software.

Thismanual is not a process where you follow every page every time. It is a guide broken down into sections with step by step instructions for doing different processes you may encounter. Not all sections are applicable to every project or person.

  • There are different sources that data can be obtained from.
  • The primary GIS software program used in this tutorial is Global Mapper.It is somewhat expensive butallows for greater accuracy with less effort than other free or less expensive tools. There is a section on using free or less expensive tools for those who do not have Global Mapper.
  • This tutorial goes into some detail on using GIS software. Some of this information is not needed if you do not wish to be as detail oriented about the process or do not have access to Global Mapper.
  • In Global Mapper you can load many different data sources and sometimes some work is required match them together. The tutorial coversdifferent scenarios toaccomplish this.
  • There are sections for importing into specific golf architect software programs.

Scenarios

Examples for some typical scenarios are given below. Every project takes sections from each part, Data Sources, GIS Software, and Golf Architect Software. These examples show the sections you’d use within each part for a complete step by step process with the given criteria.

LiDAR using Global Mapper exporting to Red Chain:

  • LiDAR Data (Data Source)
  • SAS.Planet (Data Source)
  • Global Mapper (GIS Software)
  • Red Chain (Golf Architect Software)

PGA 2000 Data using Global Mapper exporting to Red Chian:

  • LiDAR Data (Data Source)
  • SAS.Planet (Data Source)
  • Global Mapper (GIS Software)
  • Red Chain (Golf Architect Software)

NED using free GIS tools exporting to PGA 2000:

  • GeoComm(Data Source)
  • SAS.Planet(Data Source)
  • 3DEM (GIS Software)
  • Headgate(Golf Architect Software)

Chapter 1: Data Sources

Elevation Data

Elevation data is a digital representation of real world terrain. It is used to generate plot wide elevations for doing real course renditions or fictional courses based on real locations.

Elevation Data Quality

How accurate elevation data is depends on its resolution. It is similar to the resolution of an image in that a higher resolution produces sharper detail. Think of it as a grid of measured elevation points. The resolution is measured by how far apart these points are. In a 10 meter resolution file each point on the grid is separated by 10 meters. A 1 meter resolution file is a higher resolution because there is only 1 meterbetween each point on the grid. There is also vertical resolution which indicates how accurate elevation measurements are. This is typically around 0.1 meters.

With 10 meter resolution you get good plot scale elevations but you still have to do the fine detail work like green contours, mounding, bunker shaping, etc. With 1 meter resolution most of the contour work is done. Sharp edges still get rounded of so things like bunker lips or edges of tees and green may need to be fixed. Resolutions worse than 30 meter are not very useful unless your area has extreme elevation changes.

LiDAR Data

Light Detection and Ranging (LiDAR) data is elevation data scanned using lasers. It is similar to radar except it uses laser light instead of radio waves. Using the known speed of light the timing of the reflection of the laser beam back to the source is used to determine the distance traveled. Typically for elevation data this is done from an airplane. Reflections of trees, buildings or other objects are tagged so that they can be removed and only the land heights remain.

LiDAR in its raw form varies in resolution depending on the amount of obstructions in the scanned area. Even so it is typically high resolution (usually 1 to 3 meter) across most areas and the in play areas of golf courses typically have minimal obstructions.

LiDAR Downloads

Most of this data is gathered by governments and in the public domain, available for download for free. Currently it is not aggregated on one central site though. The best thing to do is Google LiDAR along with the state, county or city of the location you are looking for. There are a few national sites for the US that you can check as well that have spotty coverage:

For about half of the state of Wisconsin LiDAR data is available at

DEM Data

A Digital Elevation Model (DEM) is a format for elevation datathat multiple sources of data can be put into. LiDAR data you download may already be processed into a DEM file.

The United States Geological Survey (USGS) has created a National Elevation Dataset (NED) compiled from multiple sources. It primarily uses survey maps but also combines digital photogrammetry and someLiDAR and InterferometricSynthetic Aperture Radar (IfSAR) which is a form of scanning using radar. If there is not specific LiDARavailable for the area you need this is typically your next best option. Most of the US is available in 10 meter (1/3 arc second) resolution although some areas do have 1 meter (1/9 arc second) resolution and some areas only have 30 meter (1 arc second) resolution.

DEM Downloads

Below is a list of sources you can download DEMs from:

  • The National Map - Primary source for downloading NED data for Global Mapper.
  • GeoComm - NED data in a file format then can be opened in free tools. Changes to the NED may not be updated here as often as they are on The National Map.
  • GeoBase - DEM Coverage of Canada.
  • NetGIS - DEM coverage of Europe.

This tutorial goes into detail on downloading from the following sources:

  • The National Map
  • GeoComm

Imagery

Using satellite and other aerial imagery as a transparency over your plot allows you to accurately trace fairways, greens, tees, water, etc. and place objects in the correct location on your plot.

Image Quality

Generally a higher resolution image makes it easier to layout your course. This tutorial explains how to get the highest resolution image from your source. It's not the only factor though. Shadows, the season an image was taken in, how old an image is, etc. can make different parts of your image difficult to use or inaccurate. Because of this it is better to use multiple images if they are available for your location.

Imagery Sources

Below is a list of sources you can download imagery from:

  • Google Earth/Maps - High resolution color imagery around the world. No complete coverage of any specific area.
  • Microsoft Virtual Earth - High resolution color imagery around the world. Complete coverage of the US.
  • USGS Seamless - Black and white imagery and topographic maps covering the entire US. Color Imagery in some areas.
  • TerraServer - of the same imagery available from USGS Seamless.

Downloading Imagery

There are several programs for downloading imagery.

  • SAS.Planet
  • Terra Incognita
  • Global Mapper
  • Google and Microsoft APIs

This tutorial goes into detail on

  • SAS.Planet – This program makes downloading imagery from many different sources the easiest.
  • Global Mapper
  • Google and Microsoft APIs - Mostly here for historical reasons as a backup plan. I developed this method before programs existed for doing the same task.

Downloading

The NED data can be downloaded from The National Map ( /)

  1. Zoom in to the area you want to download.
  2. Click on Download by Bounding Box
  3. Draw a box around the area you want to download.
  4. Put a check mark next to Elevation and click next.
  5. You may also wish to put a check box in US Topo, Orthoimagery and Contours.
  6. Put a check next to the best resolution from available (typically 1/3 arc-second). It does not matter which format you pick ArcGrid, IMG, and GridFloat
  7. Click the Checkout button.
  8. Enter an e-mail address and click the Place Order button.
  9. When you receive an e-mail click on the Click here to download link.

GeoComm

GeoComm is an alternate source for downloading NED data. If you do not have Global Mapper this is the best place to download data has it is in a file format that can be opened in the free tools. This is a 3rd party site so changes in the NED may not be updated as often here as on as the USGS’s own site, The National Map.

To get started you need to register for a free account on the GeoComm Site. Once you've done that you're ready to start looking for the DEM. Tiles are sorted by state, county and city. If you know the town or city where your course is located try doing a Google search to find the county in which it resides. Another way to find the county is to gradually zoom out in Google Earth until it displays counties.

  1. Open the GeoComm Site and select the state your course is located in.
  2. Select the county the course is located in.
  3. Select the first item on the list "Digital Elevation Models (DEM) - 24K".
  4. Select the city or town your course is near and click on the green download button to the right.
  5. Depending on your location you may have more than one resolution option to download. Download the highest resolution available. For more on resolutions see the DEM Overview.

SAS.Planet

SAS.Planet is a free program that makes it easy to download and stich together imagery from many sources on the internet including Google and Microsoft. SASGIS is their website and it is in Russian but the program is in English. To help avoid trying to navigate a site in Russian, here is the download page from Bitbucket

One thing to note before you get to crazy about downloading imagery. Some data sources restrict the amount of data you can download from them in one day. For example with Google I have run into problems downloading imagery at the highest resolution for more than one course in a day. Google cuts you off and you can’t view any new imagery in any of their application for 24-48 hours. SAS.Planetdoes cache imagery you’ve already looked at to help avoid hitting caps.

  1. Find the area you want to download imagery. Use the mouse wheel or side bar button navigation to zoom and click and drag to pan.
  2. Click on the Selected Basemap button on the toolbar. This is the button that says the name of the data source currently selected. The default is Satellite (Google maps).
  3. Select a source. There are many choices including satellite imagery, street maps, and topo maps. Many of the sources are for specific parts of the world. Some good sources to try for imagery in the US or globally include:
  4. Google > Satellite (Google Maps)
  5. Bing > Bing Maps - Satellite
  6. Bing > Bing Maps - Bird’s Eye North
  7. Yahoo! > Satellite (Yahoo!)
  8. ESRI > ArcGIS.Imagery
  9. SAS.Planet does not make it obvious what the highest resolution zoom available is in an area as it just gets a little pixelated when you zoom past the maximum resolution. There is however a process you can use to determine the highest level available.
  10. Zoom in to what looks like the closest level before the image starts to pixilate (for Google Maps this is usually in the 20-22 range).
  11. Right click on the image and select Show Primary Map Tile. If a tile image opens then imagery is available at this zoom level.
  12. Zoom in one level if an image tile opens or zoom out one level if no image tile.
  13. Repeat the process of right clicking and select Show Primary Map Tile until you find the highest zoom level that opens a tile image.
  14. Click on the Selection Manager button (second from left on the toolbar) and choose Rectangular Selection.
  15. Click one corner of the area you want to download. The mouse begins drawing a blue box to outline the download area.
  16. Click the opposite corner so that everything you want to download is inside the blue box. The Selection Manager dialog box pops up.
  17. On the Download Tab under the Map: choose the source you want to use from the drop down.
  18. Under Zoom: choose the zoom level you noted earlier.
  19. Check Try to re-download missing tiles
  20. Click Start. SAS.Planet will download all of the needed tiles. Click the Quit Button.
  21. Click on the arrow on the right side of the Selection Manager button and select Last Selection.
  22. Click on the Stich tab.
  23. Set the Output Format to what you want to save the image in.
  24. If you have Global Mapper the easiest format to save it in is an ECW (Enhanced Compression Wavelet) file. This is an image format designed specifically for large satellite photos to improve compression with emended coordinates.
  25. If you don’t have Global Mapper, save it as a regular image file such as JPEG and under Create georeferencing file check.kml file. This saves the coordinates of your image in a separate file.
  26. To the right of Save To: click the … button and choose the location you want to save the download.
  27. Make sure the correct source is set and set the Zoom level. To get the maxium resolution use the zoom level you found earlier. to the maximum level you found earlier.
  28. Set the Quality to 100%
  29. Click Start. The program shows a progress bar for downloading. When it is finished the file is saved to the location you chose.

Data within Global Mapper

Global Mapper has some sources of data built into it. If you don’t have at least one file with metadata then you need to download something within Global Mapper to use as a reference for where to place the rest of you data.

  1. Either click on the Download Free Maps/Imagery from Online Sources button on the Global Mapper start screen or go to File > Download Online Imagery/Topo/Terrain Maps…
  2. In the Select Data Source section select the data you want to download. The World Imagery source under Popular Sources or Imagery is good for satellite imagery.
  3. In the Select Area to Download section specify a street address or latitude and longitude.
  4. Set the Within option to 1 Mile. You can crop the image down to only the area needed later.

Google Earth and Microsoft Virtual Earth APIs

This section is mostly here for historical reasons. I developed this method before programs like SAS.Planet existed to download imagery. If for some reason you can’t download imagery from one of the program that now do this, use this is process as a backup plan.

Both Google Earth and Microsoft Virtual Earth themselves do not provide a way to save imagery at high resolution. The most obvious solution us to use the Print Screen key. Doing this you'll either need to fit the entire plot on screen and have a low resolution image or stitch a bunch of screenshots together in a paint program. The method I developed below is to use the Google Maps or Microsoft Maps API to create an oversized webpage and use a browser plug-in to take a screenshot of the entire webpage.

Location Coordinates

Before you begin you need to find the latitude and longitude coordinates for some points around your location:

  • Northwest corner of the plot.
  • Southeast corner of the plot.
  • Approximate center of the plot.

You can do this is with Google Earth. If you do not already have it, download and install it before proceeding.

  1. Open up Google Earth.
  2. Go to Tools > Options.
  3. Under Show Lat/Long change "Degrees, Minutes, Seconds" to "Degrees" and click OK. This gives the coordinates in decimal degrees.
  4. Find the location you want to use. You can do this by panning and zooming the image or by entering a city/address in the "Fly to" field in the upper left.
  5. Once you have your location in view double click the N on the compass in the upper right. This rotates the image to ensure north is facing up.
  6. Move your mouse to the point you want to use as the northwest corner of your plot. Give plenty of room for the north and west boundaries of your course. If there are land features visible outside the course you may want to include these too.
  7. Write down the latitude and longitude shown in the lower left portion of the screen including any negative signs. Negative latitude indicates the Southern Hemisphere and negative longitude indicates the Western Hemisphere.
  8. Repeat steps 6 and 7 for southeast corner and the approximate center of the plot.

Displaying and Saving the Image