This is a sample of what you get after it is processed. The yellow colors in this view come from the Classify Vegetation Height.tif background map.

Transcription

1 This is a sample of what you get after it is processed. The yellow colors in this view come from the Classify Vegetation Height.tif background map. Yellow indicates places where the first and second return are basically the same. For this map, you can see a swamp in the upper right hand corner, the lawns around the buildings (shown green here), playing fields, and a golf course in the upper left with fairways. In this screen, the roads are seen as yellow (but other backgrounds show them well so don t worry). The green areas are generally thickets but may literally be a single bush. It may be a good time to save this file; do it regularly so you don t lose your work.

2 Below is what this map looks like at 2X scale and this area will be looked at in detail in the next few slides. The green, rectangular object is a school building with lawns and a sports field around it. The area to the north has had some lumbering and shows some yellow areas as well as some green areas showing where the lumbered areas have started to grow up as saplings. Remember, as you are field checking you will find differences from what you think is shown -- what appears to be an area of saplings may be something different.

3

4

5 Sometimes features are easier to see with just the shaded relief background. See the difference between the left and the right maps. In the shaded relief map, the arrow points to a rather obvious line, which is a stone wall. When you are field checking, this kind of information is useful to have.

6 Now you are probably thinking about what to do with all these different ways of looking at the data. If you are working with a tablet, you can make the changes back and forth with a click of a mouse. When you need one kind of information, you bring that up. This is a real advantage of mapping with a tablet in the field. If you are working with a map board (which might be advantageous in rocky terrain or bright sunny areas) there is a way to get all this data available. It may not be as easy as with a tablet, but dropping your tablet as you walk in a rocky area might not be a desired result

7 To see all the data using a map board, put a couple of registration marks on the map. In this case, we'll use two aid station marks. You now can print out all the layers that you think are going to be useful (if printed at the same scale), then each printout can be moved under your translucent drawing surface and be seen. It should all line up. Yes, this isn t as easy as you might like but it may be useful for some purposes. It is also why many mappers prefer tablets for field checking. They also put in the data once and don t have to transfer it later. (That transferring is done by scanning your field notes and then using them as a background map.)

8 This map has been made with.5 meter contours. It is a bit busier but may show a few more things as you field check. (Remember, you can always hide the form line contours which are the.5 meter ones.) The map on the left has vegetation, and the one on the right has removed the vegetation and kept the hill shading and contours. The next slide has the detail of the right image, enlarged.

9

10 The detail is quite good, and working at this scale with the.5 meter contours may be very helpful when field checking. One other thing that is helpful is to exaggerate the hill shading. To do this, go to DEM at the top of the screen and then look in the menu for Create Hill Shading. Click on this and then look for "exaggerate" and change the value to 10. (Default is 4.) This amount of exaggeration allows you to see a bit more of small knolls but in flat, swampy areas, it will be very bumpy. When asked, save a separate file as hill shading 10 so you can work either with this background or the one produced by the default. To have this exaggerated shading only, go to the Background map menu, then Manage and click to get the visibility eye for only one you want. The eye is in the left hand V column.

11 Below is the exaggerated shading with.5 meter contour of a swampy area. Notice that there is a lot of stuff there and, given that a.5 meter difference will make a new form line contour, it is very busy.

12 At the same time, the exaggerated hill shading can show some very useful things. The stone wall was pointed out earlier; this slide shows what appears to be a long depression. This depression is actually a trail that has had some erosion so it is slightly lower than the area around it. You actually can see where you need to draw the trail. This trail doesn t show up for its entire length but here, this visibility really does help.

13 One very useful background is the LasIntensity. To get this background, go to the Background Map menu and click on Manage. Click on all the eyes on the left hand side of the table to remove them, except for the one for LasIntensity that is probably last on the list. The image seen below is what you now have. This data shows how well the Lidar was reflected. Reflection is very good from hard surfaces or dense leaves, somewhat good from bare dirt or sand, and hardly at all from a field because the waves are basically absorbed by the ground and grasses. For mapping parks and schoolyards, this is very helpful. The left arrow points to the school building, the upper right arrow points to light gray which is a dirt road around the school building, and the bottom arrow points to the paved road and adjoining parking lots.

14 This is the same LasIntensity background which shows a number of things well. The baseball diamond is the most obvious and the fence with the dugouts is also quite easy to see. Of note is with the.5 m contour, you can see that the design of the field had a high point going toward center field so the field would drain. Some other things of note are related to the golf course which is in the left part of the map. The fairways generally show lighter than the rough so these can be delineated. Individual trees show up as black, so they can be placed precisely on the map. In this area, there are three sand traps that also show up as light gray (see arrows). The cart path also looks like a dark gray line.

15 In this segment of the map which is near the school building and parking lot, there are some black dots near the contour line in the lower right part of the image. These show different reflectivity. They look like hard objects similar to the pavement and building. These are actually boulders and reflect radiation well. This image allows a field checker to see exactly where they are.