BG-Map Surveying Tip

Using Paper Maps and a Scanner to Map Dense Plantings without the Need to Survey With a Total Station or GPS

By Gergely Boroczki
Horticultural Intern, The Holden Arboretum

Updated 5/1/01


Editor's Note:

This document explains a simple technique to map complex densely planted areas without the need to survey with a total station, GPS, or tape measure. It involves marking up paper maps with the locations of the plant masses, scanning the maps, and overlaying the scanned images onto the AutoCAD basemap. This technique would be useful for mapping areas such as shrub masses and perennial beds. Paper maps could be given to gardeners or curators for markup of plant outlines.

As an alternative to scanning and overlaying, the marked up maps could be entered into BG-Map through use of a digitizing tablet (See Desert Botanical Garden Converts from Paper Maps.

To enlarge any of the screen shots shown in the article, click on the image. Click the Back button to return to the article.


The Rhododendron Garden is one of the most popular areas in The Holden Arboretum. The Garden contains hundreds of different species and/or cultivars located in many beds of various sizes and shapes. The plants, naturally, have grown close to each other, making it a difficult task, at best, to identify and map the individual plants and plant groupings. However, with time being of the essence, this year the mapping has progressed using a method that is based upon the blending of human knowledge and memory with the modern technology of BG-Map and BG-BASE.

Preparation for Mapping - Surveying the Bed Outlines and Creating Blank Bed Maps

The very first step was measuring the bed outlines and plants outside of the beds using the total station. Downloading the surveyed points to BG-Map using NPO's and drawing the bed outlines using the points in AutoCAD was the next step. The only information recorded about the location of the plants was the beds in which they were planted. These bed locations were entered into BG-BASE. From BG-BASE, we printed a list of the plants in each bed. And, we printed a map, which contained the bed outline, a scale in meters (scaled so that 1 cm in the map was equal to 1 m in the field) and a North arrow.

Fieldwork at the Helen S. Layer Rhododendron Garden - Hand Drawing the Plant Locations

Marking up paper maps in the fieldBilly Isner the Rhododendron Garden Foreman and his assistant Mark Bir surveyed and marked each plant on the bed maps by hand. During this project, the most important component was Billy's knowledge, gained during the 34 years he has worked in the Rhododendron Garden. For measuring the canopy of the shrubs Mark used a bamboo-pole, marked at intervals with colored tape, blue at 1 m and orange at half meter intervals, instead of using a measuring tape. Billy marked all the plants on the map with their name and accession number corresponding with the labels by the plants which were not always easy to find.

Entering the Plant Locations into BG-Map

1. Scan the Bed Map

·         Using any regular scanner, scan the map. I recommend using 'jpeg' file format, because that will result in the smallest size image - it is important because a large one would slow down the process noticeably. After scanning decrease the gamma balance enhancing the map, visibly.

·         If you have a large formatted map and a small scanner, divide the map into smaller pieces and scan them separately.

2. Attach the Image of the Bed Map

·         Start BG-Map.

·         Using the (pan) button go to the area where you want to insert the map and notice the coordinates.

·         In BG-Map, in the generate menu, select 'generate normal quadrant'.

·         In the AutoCAD toolbar select (image).

·         Select attach and browse to the directory where the maps were placed and open the desired image.

·         In the next screen I suggest that you not modify the settings. Simply choose the 'specify on screen' option in the case of: 'insertion point', 'scale' and 'rotation' (note a checkmark by each). Then select OK.

·         The next step is inserting the image into the map.

a)         Hold a single left-click and move the cursor from the starting point to scale the image (don't worry about the size as it will be modified later).

b)         When you have reached the size of the original bed, stop enlarging the image with a single left-click. Then, rotate it, if you wish.

c)         When you are satisfied with the image, finish with a single left-click.

Click to enlarge

3. Modify the image

·         Because we need only the bed, it's best to eliminate the surrounding blank space. But before doing so, I recommend zooming to the image so as to cut away the blank area as precisely as possible. In the AutoCAD toolbar select (zoom-window), and zoom to the 1/3 or 1/2 of the image.

·         In the AutoCAD toolbar select (image-clip).

·         Select the image with the mouse (single left-click on the border of the image).

·         Since we want to create a new boundary, type 'new' or enter if that's the default value.

·         Choose the 'polygonal' option (unless you have an exactly square-shaped bed)

·         Create the new boundary slowly, step by step, moving only small distances (tip: try not to leave too many blank spaces or cut into the image).

·         If you want to move the image just use the (pan) with a single left-click and select 'exit' to quit the pan.

·         When you have finished cutting around the image, select single right-click.

Click to enlarge


4. Overlay the Image Onto the Map

·         The next step is to overlap the existing bed in the map with the image.

·         First scale the image by approaching same size, gradually.

·         In the AutoCAD toolbar select (scale), select the image, specify base point (single left-click right next to the image) and specify scale factor (it's recommended to change it just a little bit every time - for example, to enlarge the image type: 1.001 or 1.01; to decrease it type 0.999 or 0.99 - you might have do this several times to get the best result).

·         To move the image, in the AutoCAD toolbar select (move), and select single left-click, releasing it after you have moved the image to the desired place.

·         You can also rotate the image using the (rotate) icon.

·         Process is complete upon perfect overlap.

Click to enlarge


5. Add the Plants

·         In BG-Map under the 'Map' menu, choose the 'Add a plant' option.

·         Browse to the desired plant.

·         If it's a MASS, then checkmark the group planting option.

6. Edit the Group Outlines

·         After you have finished the mapping, generate the same quadrant and double-check the group outlines.

·         To modify them, select the edit group outline command in AutoCAD under the plants/objects menu.

Here's The Final Result

Click to enlarge


Gergely Boróczki
Horticultural Intern
The Holden Arboretum