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First, make sure you have the latest version of Global Mapper. If the problem persists in the latest version, please send a description of your workflow, a copy of your data (if possible), and the results to Blue Marble Geographics Support (email@example.com). This will ensure that the support team will be notified of the problem and can work on a solution.
I am currently wondering about the analysis of cast shadows based on the the terrain.
My background is, that I am trying to simulate the near shading effects by trees, buildings and other elevated objects onto lower terrain to see if the terrain behind / below will be shaded during specific hours of the day.
I figured out, that the shaded relief function allows for setting of different sun angles and azimuth and so I tried to work with this. However, it appears to me, that this functionality will only display, whether or not a specific area would in theory receive direct sunlight but it does not cast / show the shadow, which an object will throw.
So for example, I am attaching a view from a 3D model, where I overlaid three hill shading options. The model is located in Yamagata, Japan.
Option 1 (10:00 am)
Sun angle 24.5°
Option 2 (12:00 pm)
Sun angle 28.5°
Option 3 (14:00 pm)
Sun angle 20°
I am aware, that the above numbers are not 100% correct, but it is accurate enough for my purposes.
My point is, that the programm just creates dark areas, where there is no direct sunlight, but it does not cast shadows. In this case, there are two buildings in the centers, which are roughly 30m and 40m high and they would probably cast quite far shadows behind them.
Is there a way to do this? I would like to see, how far shadow is reaching but right now it seems that the programm is not doing that.
Thanks for response, Katrina. I have seen the excellent webinar. The issue seems to be with the higher point densities of the photo generated point cloud. I will continue to work with smaller sections. I don't know if there are any recommended settings for such a file as a starting point. Using '1 point' spacing for the gridding seems to tight, and 1 or 2 meters may be to large. There are so many settings, it is a little daunting. I know there is personal training available; however, is there a chance to just talk with someone on the phone for a short conversation? BTW, the link for the case study above did not work.
I'm running this technically under a script, but it's also happening in gui mode so under here it goes. Version is 17.2; can provide dongle details if required.
I'm creating a bunch of buffer areas that have to be precisely on the whole metre. I find, though, that when I create a buffer - be it from the little button or LAYER_BOUNDS_EXPAND, it's always up to 35cm or so out (yes, when checking metadata, not just zooming). My original areas are showing up as precisely on the metre. What's happening?
We have a bunch of huge projects coming in that require this not to be happening so help would be very very much appreciated, even if just to see what I am missing.
Alternatively, a way to make elev grids etc line up with the metre is also welcome
I’ve been playing with the hydro-flattening and have another problem I’m not quite understanding. I’m testing the functionality of different gridding methods and am having some problems when I combine the bin methods with hydro-flattening polygons (note this is just test data). As you can see in the screenshots, the TIN method respects the boundaries of my polygon, whereas the bin method connects parts of the polygon. You see in the screenshot that the bin method has cut part of my data off. The bin parameters are set to only 1m while the gap it is bridging is about 75m.
The issue is that your calculation of the shader levels in meters from the feet value was using a conversion value of 3.2808 hard-coded in the DEFINE_VAR commands. Internally Global Mapper uses 3.2808430145964.
This discrepancy caused your calculated shader levels in meters to be very slightly higher than they should be, so the area contour heights were just barely below the cut-off in the shader when internally converted from feet to meters using the more exact conversion. Because the shade definition had BLEND_COLORS=NO set, the slight difference caused the lower range to be used rather than the higher range.
I have fixed this in your script by defining the contour intervals using the following:DEFINE_VAR NAME="CVT_FT_TO_MT" VALUE="3.2808430146"DEFINE_VAR NAME="CONTOUR1" FORMULA="(%START_CONTOUR_FT% +0) / %CVT_FT_TO_MT%"DEFINE_VAR NAME="CONTOUR2" FORMULA="(%START_CONTOUR_FT% +1000) / %CVT_FT_TO_MT%"DEFINE_VAR NAME="CONTOUR3" FORMULA="(%START_CONTOUR_FT% +2000) / %CVT_FT_TO_MT%"DEFINE_VAR NAME="CONTOUR4" FORMULA="(%START_CONTOUR_FT% +3000) / %CVT_FT_TO_MT%"DEFINE_VAR NAME="CONTOUR5" FORMULA="(%START_CONTOUR_FT% +4000) / %CVT_FT_TO_MT%"DEFINE_VAR NAME="CONTOUR6" FORMULA="(%START_CONTOUR_FT% +5000) / %CVT_FT_TO_MT%"DEFINE_VAR NAME="CONTOUR7" FORMULA="(%START_CONTOUR_FT% +6000) / %CVT_FT_TO_MT%"DEFINE_VAR NAME="CONTOUR8" FORMULA="(%START_CONTOUR_FT% +7000) / %CVT_FT_TO_MT%"DEFINE_VAR NAME="CONTOUR9" FORMULA="(%START_CONTOUR_FT% +8000) / %CVT_FT_TO_MT%"
The conversion factor is defined in one place rather than repeated. I used a value that was rounded up at the 10th decimal place rather than use the full exact conversion just in case there is some round-off error somewhere. The very slightly larger value will cause your calculated levels to be very slightly above the GM values rather than below as they are now, causing the proper color to be used.
Let me know if I can be of further assistance.
Global Mapper Guru
You can use Analysis > Measure Volume Between Surfaces
- DTM2 is the layer to subtract from
- DTM1 is the layer to subtract
Measurements:Total Volume Between Surfaces: 9947.185 cubic metersCut Volume: 8038.4232 cubic metersCut 2D Surface Area: 4931.6 sq mCut 3D Surface Area: -Fill Volume: 1908.7617 cubic metersFill 2D Surface Area: 13809 sq mFill 3D Surface Area: -LAYER_COMPARE: DTM2.tifLAYER_BASE: DTM1.tifREPORT_TIME: 01/06/2017 12:23:07AVG_Z_DELTA: 0.327 mMAX_Z_DELTA: 5.345 mMIN_Z_DELTA: -1.599 m
- Make sure you have assigned the elevations first then (Vertex Editing > Edit Feature Vertices)
- Select the lines
- Advanced Feature Creation Options > Create Point Features Spaced Along Selected Features
Alternatively, if you have reasonably clean contours you may be able to convert them to lines by creating area features based on the contour colour values and then converting those to center lines:
- Right-click the raster layer
- Create Area Features from Equal Values in Selected Layer
- Choose Only Create Areas for Selected Colors and enter the RGB value of your contour e.g. 0,0,0 for black
- Select the newly created area features
- Right-click > Move/Reshape Feature(s) > SIMPLIFY
- Right-click > Move/Reshape Feature(s) > SMOOTH
- Right-click > Advanced Feature Creation Options > Create Area Skeletons/Center Lines
- Join any gaps in the new contour lines:
- Right-click > Crop/Combine/Split Functions > COMBINE
- Repeat steps 5 & 6 to reduce the points and smooth
This is an example I created using the above workflow - took around 10-15 minutes. Using the Image Swipe Tool I have shown the original raster on the right and the results of the process above on the left. The image below that shows the raster below the new contour lines.