Mesh creation issues

  • Reason I ask is I would like to try and use a 30 metre SRMT Level 11 Regional mesh with 5m urban and 1 metre airport meshes at higher levels say level 13 and 14.

    May have to trim to avoid masks.

    But what about masks where there are no adjoining areas, like an island or airport doesit matter? Masks won't interfere right?

    Because level layers

    For Science

    Yeah Yikes, Spikes read above :/

  • Hi,

    Masks for islands are seldom an issue since the merging terrain is generally sea at zero altitude.

    Scenery borders, with or without masks, are much more of an issue when falling on ground. How to stop then the mesh without causing walls ?

    The smoothest transition is achieved by first stopping HR mesh and leave an outer band of mesh compiled in Level 9 or so.

    But how then should another editor add a neighbouring scenery ?



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  • Hello chaps

    I have been working on that spikes issue in elevation meshes and it seems my hypothesis that grayscale colour depth May be the issue indeed.

    My thinking was that the game and geoconvert only supports 16bits per pixel for height information.

    Often higher resolution elevation meshes use more bits per pixel for height information.

    For example 5 metre meshes I have tested use 32bits per pixel

    and 1 metre meshes I have tested use 64bits per pixel.

    Basically if the height information per pixel is not 16bit the game cannot interpret the height and thats when you see spikes.

    To test I converted a 1 metre 64 bit per pixel mesh data of Camden airport near Sydney ;)

    The results were the usual spikes.

    64 bit per pixel elevation map

    Usual result SPIKES, Nothing to see here.

    Next I used GIMP to change the geotiff from 64 floating point to 16 bit integer precision per pixel using the IMAGE > PRECISION menu.

    With the result below clearly showing terrain rather than spikes, but still at 20,000 feet.

    64 bit per pixel elevation map converted to 16bit integer in GIMP

    I'd say that this is progress and although clearly not the complete solution, I think its safe to say that my original hypothesis is partially correct.

    The game and geoconvert only understand 16 bit per pixel for height data precision, and 32/64 bit height data found in high resolution elevation maps results in spikes.

    BTW : this is two maps side by side, will test with a single map. Also maybe if I darken the colours in GIMP I can make the terrian lower to be level with the ground. Im no GIMP expert so won't bore you with the details but will update when theirs progress to report.

    Maybe after my afternoon map. || :/

    PS: Why are my images blocked?

    I decided to forgo my nap and instead used the Colour > Brightness menu in GIMP to darken the input elevation maps.

    I darkened the left and right side maps by different amounts -.100 vs -.110 just to see the difference in height of the two maps I used.

    The results, show that indeed the terrain has been lowered closer to ground level.

    Those odd spikes I need to think about doh I'd say I'm making some progress on the spikes issues.

    PS: Can I get my images unblocked please.

    Edited 2 times, last by ozhomeroz (October 26, 2019 at 1:16 AM).

  • More progress, at this rate I will be waiting a long time for that nap, anyhow I digress.

    I have made some discoveries and need some advice .

    One thing I noticed was that the edges where the two maps meet is not parallel, Mmm.

    I imported the original ASC file to Qgis and changed the CRS from "EPSG:28356 GDA94/MGA 56" to "WGS84:4326" which to my knowledge the game uses.

    Any one know how to change the projection angle as this info is available in a accompanying PRJ file.

    Picture below shows how the map edges are not parallel.

    [Blocked Image:]

    Also I think I have discovered the cause of the few remaining spikes. I noticed that their was a gap in places between the mesh I added and the under lying default mesh. Funny thing is the height in the gap is lower than the default mesh terrain. :/

    [Blocked Image:]

    Only some sides of the added meshes have gaps, and this is where the few remaining spikes appear.

    On sides of the mesh without gaps there are no spikes.

    So I believe changing the projection angle as stated previously would remove these gaps and thus the spikes as well.

    Another dirty method I will try is adjusting the extent in the FTW and mesh_conv.tmc files to remove the gaps and the spikes.

    Don't know if it will work but until I discover how to change the projection angle to remove the V shaped gap between the two maps, its my only shot.

    Another Picture of those gaps between added mesh and default mesh

    [Blocked Image:]

    So now I believe that the problem of spikes has been solved apart from those gaps which are due to the projection angle, as the added elevation map was of Australian CRS namely EPSG 28356 GDA94/MGA Zone: 56

    I believe that if you are using a elevation map based on the same CRS as the game namely WGS84:4326, you will not have these gaps or projection angle issues. And thus have to spikes as well, Yay

    Time for that nap.

  • OK the TLDR version.

    To remove spikes from your add on elevation geotiff maps.

    1) Open geotiff in QGIS, check properties and then source, if data type is not 16bit integer, that the cause of your spikes. 32/64bit Data type causes the spikes.

    2) To fix open your spikey geotiff in GIMP, its free to download and use. And the instructions are simple even I could do it. Here's how.

    Once opened in GIMP at the top of the screen click the following menu: Image>Precision and choose 16 bit Integer.

    Then export your new 16bit game comparable geotiff by clicking the File menu and selecting "Export AS". Give it a name and your done, geo-convert as normal. Test it.

    If the map is too high or low compared to the surrounding terrain adjust the brightness of your geotiff in GIMP. Brighter is higher, darker is lower in height.

    3) Next you may have to match the height of the new terrian with the underlying default mesh.

    Open the geotiff in gimp, Select the "COLOR" Menu, then select "Brightness-Contrast".

    Adjust the brightness in small amounts, Export as like in step two and geoconvert as normal.

    You may have to repeat step 3 a few times untill the height of your added mesh matches that of the surrounding terrain.


  • Darken or brighten the image in GIMP untill it matches the terrian height as described above.

    Well I wouldn’t advise this.

    First it may work on flat ground, but not in mountainous terrain where spots of your higher resolution mesh are higher than default mesh, and other spots are lower.

    Then, it alters elevations of your complete mesh.

    The solution for merging mesh borders is usually to stop your Level 10+ compilation earlier inside your scenery and leave an outer band of ground that you don’t compile higher than Level9. Points are then distant enough to absorb height differences without making walls...



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  • Dudes I think I cracked it :rolleyes:

    Let me show you the results, then explain 8|

    The first four pic are all taken from exactly the same spot

    The Location is Colo River, NSW, Austrailia near Syndey, close to Canoe Creek specifically, seemed like a good place to demonstrate the differnence Hi Res meshes can make.

    Also demonstrates SRMT is not great around hilly areas.

    Default Mesh from IPACs

    Seems the 30m SRMT mesh that I installed has slight difference over the default. Maybe IPACs compressed it to save space if their mesh is based on SRMT.

    I heard some where IPACs uses SRMT as a base

    My Guess.

    Now Colo River is the most pristine Wilderness River in all NSW they say, so it can not have uphill flowing rivers :S I fixed that in GIMP, colour picker and pencils and some hours. Good thing elevation meshes convert fast and I love Colo River.:saint:

    I have not published my mesh yet coz its not totally ready, Doh major airports are flattened, colo river is done and it includes SYDNEY.

    Now the Previously Spikey 2 meter 64 bit map converted to 16 bit in QGIS

    I been to this place many times and this looks legit, 2 metre Hi res map with out spikes.

    Next downside

    Where the 2 metre map meets the default map up close and personal, Mmm

    From up here not so bad I think.

    And the solution is easy, thank goodness for my Legendary Google noob skills


    1)Open your High Resolution file in QGIS which is free to download, Pro Tip search it on google.

    1a)Grab the geotif to drag to into QIS

    2)Select the new layer

    3)At the top of your screen, find and Select RASTER, then CONVERSION and finally TRANSLATE

    (Im shouting coz Im so happy! 8o)

    4) Use the "Output Data Type dropdown" to 16int

    5)Dont forget to "Save as File", Run it, yes really its done!!!:love:

    Convert as Normal

    * I advise against changing CRS as you will get pillars due to the image being rotated and masks and some stuff I don't fully understand.

    Anyway pillars are bad and much more perceivable than a slight in-perceivable change in orientation change due to CRS

    My comment on where High Resoultion mesh meets lower resolution or deafualt mesh is that you oversize till unnoticed just like othro.


    Edited 2 times, last by ozhomeroz (October 28, 2019 at 2:46 AM).

  • This new method is working splendidly for me, its very fast and best of all no spikes yet.

    Here's Pictures of the same location, Canoe Creek proper using different elevation meshes


    [Blocked Image:]

    30metre SMRT with Colo River modded by hand to stop it flowing uphill

    [Blocked Image:]

    2m ASC elevation from ELVIS standard but converted in QGIS to 16int

    [Blocked Image:]

    I have some back story before I tell you some cool news.

    I got into elevation maps at first because the airports around Sydney, such as as Camden, Bankstown and of course Sydney were barely usable due to prop strike due to elevation issues. So I wanted to flatten taxiways and thus began my wonderfull journey onto elevation. Upon Seeing Colo River I thought, That's not right!!!

    I previously wanted to map Colo River in higher elevation detail since it is sort of famous as a Wilderness Gorge with High Cliffs, so after downloading all the 1 and 2 metre files stopped that project. (Until now, but its a big job)

    So until our recent discoveries just now, I used a 30metre SRMT map, which had errors that needed to be fix, by hand with GIMP as its the only way I knew at the time.

    These errors mostly comprised due to my newness things as no data values, masks in coastal areas and errors inherent in the SRMT data around hilly terrain.

    I was thinking about resuming my High resolution elevation Colo Project and tested to see if I could use different levels for different elevation maps and it turns out you can.

    I used my 30 metre modified SRMT and geoconverted to Level 11

    then I used my 2m High Res ASC and geoconverted to Level 12, 13 and 14

    I placed the result of each in diferent Folders and place both in elevation\images

    I could see the both the SRMT 30m and the smaller 2 metre mesh in game.


    So on to the Final Phase

    May even have to built a mesh for that Sydney Cultivation I heard about.

    With high res Air Races through Colo River.

    I already have a hack job ready, but that Sydney cultivation looks good, may have to start a fresh mesh so its perfect.

    Edited once, last by ozhomeroz (October 29, 2019 at 2:23 AM).

  • Well Micheal, since starting this elevation caper I gotta to admit theirs a bit to it and I'm still learning.

    Till I get more mastery of the elevation process, Scotland will have to wait.

    I figure that its better to get the process streamlined so that at a later date I could do Scotland proud with an greater efficiency.

    Doing it now would be a slow process process, plus I'm already engaged on another project...

    SYDNEY, my home town.

    Let me tell you a bit about my Sydney plans and some workflow.

    The Sydney master plan is to use a 30m SRMT Regional Base map ( converted at level 11.

    Also I use higher resolution 1metre and 2 metre maps at POI and airports converted at level 12, 13 and 14.

    As I get better at this I will share what I have learnt in this thread.

    QGIS is awesome!

    If your interested in Scotland, save me some work and tell me of resolution elevation is available for Scotland.

    I would seek out SRMT maps as an level 11 base mesh, they cover a large area.

    I just gotta figure out a way to deal with no data and coast lines effiecently, which BTW Sydney also has.

  • Hi ozhomeroz,

    Thank you for sharing your interesting investigations and results.

    I just tried your method on a nasty part of mesh causing spikes. It happens to be an unsigned 8bit 5m dem

    Here's how default IPACS mesh looks like (quite good thanks to neighbouring Switzerland DLC).

    And how it looks like when I activate the geoconverted mesh (8bit source):

    Now, after translating in 16bits in Qgis according to your technique, the geconverted mesh looks like this (note de default IPACS mesh in the background)

    Default IPACS terrain without the mesh:

    So the method is not yet universal, I guess I should add a voids filling with an average value...



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  • Those look like no data pixels, I just wrote a post about using the Reclassify value tool to fix no data.

    Fix first no data before any thing.

    Test and if spikes remain then try convert data type.

    Start with a new untouched source file

    Start with a small section that fits within a Level 12 grid as shown by the Aero Scenery Tool to avoids mask which this probably isnt, but to be sure its best for now till we narrow down the problem.

    Fix no data before converting data types.

    This is what I suggest you try.

    Edited once, last by ozhomeroz (November 2, 2019 at 1:04 PM).

  • Level Order is important to consider when Geo-converting, although in my limited experience hasn't caused spikes rather omissions instead , and may be causing a conflict. I heard and read stuff and my thinking is that the different meshes work like orthoes with the layer underneath fill the space of masked areas.

    Im guessing

    Default mesh Level7

    DLC Level 10

    Your Under layer mesh Level 11 for 20m SRMT for example

    And the high detail meshes Level12-14 for 2 metre mesh

    So if your High Res map was geoconverted at level 10 the same as the DLC in my example, could be trouble and worth checking out I think

    Another issue I can see is masking with two non connect areas sharing the same level 12 cell. So if you have a level 12 cell with map data on both sides with a gap in the middle is when you will have a masking problem with one side disappearing. But I haven't seen spikes from this.

    When you download your file for your favorite area it is not always magically ready as in the tutorials.

    Some time you got to make them ready to geoconvert. With QGIS

    Luckily we have QGIS and in the coming weeks I will post on my methods and work flow for making the Sydney mesh Project thingie for others to digest that will help the communities knowledge base on elevation mapping. Rather than take individual requests, just no time for that but such a walk through can increase the communities knowledge of QGIS and some of its benefits.

    Be sure to read the fine elevation tutorials on the forums, as I won't be covering much that has already been covered so superbly so you will need to study up on that.

    Rather it will focus on preparing your map when its not ready to geo-convert using the Sydney project a an example. Because when I started it definitely was not ready with spikes galore.

    More stuff incoming.

    Edited 2 times, last by ozhomeroz (November 2, 2019 at 11:21 PM).

  • For Geoconverting levels, you can refer to my afs2-sdk-geoconvert-tool-basic-reference-unofficial-guide, there's a chapter dedicated to mesh. The same grids and rules apply as for orthophotos, except that the "no mask" option has no effect on mesh geoconverting.



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