What's happening with my terrain?

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We're planning a building scheme at Church and I've produced the 3D model of the architects plans to help members understand what it will look like, but the terrain is refusing to do what I think I'm telling it! 


I'm currently using HDA 2015.  I started with HDI 2015 to model the building, then decided I wanted to add the terrain as we are re-modelling the front entrance which requires ramps/steps and flower beds.  This means I'm adding terrain onto an existing building design, rather than the ideal approach of terrain first.


I started with just 3 Elevation Lines across the plot, as most of the plot follows those lines - 6' at the rear of church (the sidewalk shown), the front of church (level with where the low retaining wall kinks to the left) then a short one across the car park entrance (between the railings at the bottom of the image).  I expected the whole of Church behind the middle elevation to be flat, then the car park to (reasonably) slope down to 0' at the entrance - it is rather like a fish-bowl.  However the sidewalk on the right of the image looked like a roller-coaster rather than being perfectly flat.


I therefore deleted those lines and just drew an Elevation Area across the whole of the building, extending out past the edge of our Terrain Boundary, all at 6' high.  This is what you can see highlighted on the 2D image. This should surely ensure the entire terrain is level?


Yet if you look at the rear-right of our property, it looks like a skateboard park with all the weird elevation changes riding up the walls etc.  All of this should be at 6' completely flat (at this stage).


Any ideas what is going on?


I've done a Rebuild Terrain to try fix it but it's not having any effect.


PS - is there a concept of 'send to back' in HDA?  I used a .jpg image of the architects floor plans to build the walls in the right place, but now I'm doing terrain, I deleted that image and added a different one with the terrain boundaries on - but it is always 'in front' of everything, so I can't click on walls/furniture etc. The same is now happening with the Elevation Region, which is in front of the image, which is in front of the building.







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I cannot tell much from the images posted (elevation views would be more useful)


Where you require flat terrain use terrain flat area, otherwise use elevation lines or splines for where you do not want it flat.


Do not place differing value elevation objects too close together, space them out, they are programmed to create a gradient between differing value objects, trying to micromanage those gradients is not worthwhile to try. You use as few elevation objects as you can to get the effect you want.



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  • Solution

as David mentioned take some Perspective overview shots the doll house overviews directly above the building don't let us see what the terrain is doing and a terrain perimeter /lines pic too.


The terrain will auto build at 18" below the main floor ( level 1 is 0") of the building if the building has a foundation , so depending on how you measured your elevations and what they are referenced too you may need to make allowance for the 18" in your height calcs. At least in Pro the default height is changeable in HDA I'm not sure.      note: The default distance is different for different types of foundations.


you can use the Flatten pad checkbox to flatten the terrain under the building to start ,setting the terrain height right in relation to the building ,then working with just a few terrain lines to get a gentle slope.  the elev. numbers for those lines must be calculated from the Default height AND using + or - with your numbers. Eg if you input 0" at the driveway it would actually be the same height as the terrain at  the building which is always 0"  (The main floor of the building is 0" too but is really 18" above the terrain ( as above) so it can get a bit confusing,so ignore the building) which may account for the "fishbowl" . you will need to use negative numbers since the build pad is 0" and up the back is +72" so the front would be say -12" then -36"  not 0" at the driveway to get a slope.


Moving your camera out to the side should let you see what's happening in the 3d window while you change numbers on the EL lines , (you can split the view windows with Shift-f6)


You can use Display Options for each and every different view 2D or 3D cameras to display or not certain items or lock items so they can't be selected by accident. Some objects have a front group/back group option but I think that refers to how the program draws things rather than what is selected.


. post-25-0-78697400-1405276492_thumb.png




Ps as with all things HD there are many ways to get the same result , so hopefully other will chip in with ideas too, I am no terrain specialist but hope this helps.

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Sorry it's been a couple of days - either I missed the email notifications of my subscription to this thread, or I didn't subscribe!


In the meantime, thinking you hadn't replied, I saved the plan as a 2nd copy and deleted everything off it - doing this allowed me to keep the material defaults etc that I'd set within the first plan; I wasn't sure if they were global or per-plan (?).


I added a new background image from the architects plans with only the walls, windows and terrain showing, which makes the 2D view much cleaner than it did before.   Then I started again with my terrain.


I got most of it worked out until I added the ramp/steps to the front door, but I just about sorted that when I decided to come and see what was happening on this thread.


Your comments about the 'Flatten Pad' button were what sorted my remaining problem - I actually need that OFF because 1/8th of the plot is NOT flat - HDA was trying to bring the 4' terrain path around the building up to the 6' terrain level (aka 0" Floor) within the space of nothing.  Once I UNticked the flatten pad button, most of the skateboard park terrain misdemeanours disappeared and I was able to add one or two little elevation points to fix the rest.


Current version attached, complete with mine and my parent's correct cars. :-)




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there are settings in your User Profile for being notified of posts, and if you use the  more reply options button instead of the post button there is a check box if you want notification of posts too on the right.


If you don't find answers to your questions on the HD KB , try the Chief Architect KB , some still apply to the HD titles such as the one on stairs on sloped terrain , though I aint sure if HDA has "stair landings" like Pro.



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