TheoLt Release 10 is GO!

Watch this space for full details of the updates, the improvements and how-to’s !

Existing users should contact us now for update details.

TheoLt, TheoLt Contour and TheoLt Tools now improve the productivity of BricsCAD to V17 and AutoCAD to Release 2017 for anyone using Total Station, Laser Distance Meters or Laser Scan Data for the productions of plans or elevations.

TheoContour R10 is coming

No, we do not post often enough here.
No, we do not update our site enough.
Yes we need to work on this.
However you can be sure when we do post, it is important, it is interesting and it is new!

In this case what is new is TheoContour R10!

Its just a week or two away – we are just finishing off the installer and testing the installer.

What can you expect from the new release? You can expect what all software developers say their new releases contain:

  • More Power!
  • More Functions!
  • Easier to Use!Spline-smoothed-6_trimed

In this case it is true! TheoContour (we think) is one of the updates we are most proud of. The new features include:


  • New licensing System (easier to use, more reliable, better trial options).
  • PLY Import
  • Powerful Surface Smoothing Options
  • Powerful Line Smoothing Options
  • Better Layer Control
  • New Surface Creation Options with user definable colours.
  • Better memory management.

Surf ht shaded

Contact Us now for further details!

TheoLt R9.0

We are pleased to announce the launch of TheoLt Release 9.0

For this release our core aim has been to Streamline the Product Structure, User Interface and Settings. This is a release that has been a very long time coming but is one in which we are very proud and we believe offers a base to develop the survey tools much further than before.

A brief outline of the update follows with each module to be further detailed in posts over the coming days.

Core (Comm’s module) Updates:

  • Vastly improved User Interface with “Orientation Wizard”.
  • Pro: Un-occupied stations may now adjusted in Network via “data-augmentation”.
  • Increased instrument library matching the latest offerings.
  • Consistent Settings across ALL modules (Core, ARX’s, Contour & Office).
R9.0 Screenshot - Control.

R9.0 Screenshot - Control.

CAD Tools (ARX) Updates:

  • Support for BricsCAD V10 to V15 (including 32 and 64 bit where appropriate).
  • Support for AutoCAD 2007 to 2014 (including 32 and 64 bit where appropriate) .
  • New streamlined and consistent command set.
  • Vastly Improved features library with far more power and customisation than before.
  • theoDoor and theoDoorAlt commands allow 2 types of doors to be configured and access from the toolbars.
  • New improved Icons.
  • Improved Menus and menu loading (with Arx auto-load).
  • Consistent Settings across ALL modules (Core, ARX’s, Contour & Office)
    TheoLt Settings & Toolbars

    TheoLt Settings & Toolbars

Contour Updates:

  • Contour now included in all versions.
  • Contour settings and mesh now persist through save and loading of drawing file.
  • Multiple mesh (TIN’s) per drawing now instead of just the one.
  • New improved Icons.
  • Consistent Settings across ALL modules (Core, ARX’s, Contour & Office).
TheoLt Contour Toolbar

TheoLt Contour Toolbar

Office Updates :

  • Added, import of “level” files (gridded heights such as Nextmap).
  • “Non-Pro” version with no Network Adjustment serving as a Survey Data translator for CAD
  • Apply default coding to all points in a text data file.
  • Network adjustment updated to match Core.
  • Calculate Mesh and contour lines from points marked as “contour points” (via code list).
  • Export Mesh and contours to CAD (faster workflow).
  • More consistent zoom and pan.
  • Consistent Settings across ALL modules (Core, ARX’s, Contour & Office).
TheoLt / Office GSI File view

TheoLt / Office GSI File view

If you have any questions or would like to discuss these updates, please do not hesitate to contact us: .

Contouring 5m ESRI GRID data

Recently a 6km2 block of ESRI ASCII Grid 5m demo data has been offered for testing as benchmark for the performance of TheoContour the ‘no frills’ contouring in AutoCAD tool. I’m not sure of the origin of the data but it looks a lot like Lidar and certainly this set gives a good indication as to how TheoContour could handle a 5m post spaced Lidar swath if needed.

The point data is lovely but its dosen’t read like a map and even as a surfaced model it’s not really too useful for mapping so getting countours out of the points is a good first step to getting a map out of it. TheoContour is a great way of making that first step from data to map (getting from points to lines is something of a 1st step in most surveying processes these days!) but the sheer density of the data means a quite bit of care is needed when contouring such a big swath.

the ESRI grid data loaded as AutoCAD points

TheoContour has some slighltly tricky settings and the regular nature of the Lidar data gave me a good oportunity to get some comparative results with the sampling and sub-sampling controls.

The TheoContour contoring controls at 17/17

AutoCAD adressable memory limit: First of all its worth noting that in processing a surface conataining all 237,765 points is a bit like asking TheoContour to hold up the whole sky! It will hit the adressable memory limit in AutoCAD at some point in the calucation process, more than likely this will be at the contour processing end as this is when there is no escape from asking AutoCAD to do a lot of work in plotting the nodes on the contour lines and joining them up. In most cases TheoContour does pretty well at collating the point data so when getting to grips with a big job like this its the contour outputs that test the memory handling in AutoCAD.

First off TheoContour needs to collate the points, this took about 75s and the command line ‘thermometer’ gives you a clue as to what’s going on: running the collate command gives a command line report on completion:

Select points to include in the contour model.
Select objects: ALL
237765 found
Select objects:
Selecting and checking points.
Building Surface.
Checking Surface
Min point 269639.5000, 737484.5000, 105.0000
Max point 272659.5000, 739444.5000, 609.4700
Processed 237769 points,
Boundary Contains 4 points,
Created 475532 surfaces
Average Surface Size: 9.63
Min Surface Size: 5.69
Max Surface Size: 2040.63

This gives us a clue as how to handle this as contours. So the next step is to contour? not quite; with a big processing order like this there will be a limit to what can be done so the choice of contour interval, the smoothing step and processing strategy becomes VERY important at this point! Ignore the need for a suitable interval at your peril:

Plot and join 25million interpolated nodes eh?

Choosing data density over processing capacity: It helps to think of contour generation as ‘node building’ .  The height range is 504.47m from heighest to lowest point ; if we are to contour at a 1m interval we are aking for  503 contour lines, each one ‘joining up’ a rough maximum of  5  points per metre along its length and then interpolating nodes at the changes of direction of the isoline. So an estimate of the required nodes per contour lne might be based on the longest line (say the length of the perimeter in the worst case)  of 10,000m x 5 =50,000 nodes per polyline x 500 polylines =25 million nodes.   For AutoCAD to plot and join 25 million nodes may be possible but my system is best described as ‘average’ (i.e the mininium I can afford for an AutoCAD 20011 platform) so I think working on the basis of a 1m contour interval for the whole block at once is not viable.

A 5m interval would generate 100 contours, an 80% reduction in the amount of processing over 1m. Working with a 5m interval is going to be slow so to test the sampling settings I use a 10m interval. Straight ploylines (splines are very nice but AutoCAD will be pushed hard to generate the smoothing!) with no duplicate point checking further reduces the proessing overheads. Because of the gridded nature of the point data there is a bais to a ‘gridded’ or ‘stepped’ contour model:

10m interval sampling controls at 10/2

10m interval sampling settings at 10/8

By increasing the sub-sampling rate step by step the ‘stepping’ effect of the contours begins to be reduced. Each increase in the sub-sampling rate increases the processing time so there is a point where the sample rate needs to be reduced once a good sub-sampling result is achieved: the goal is to commit to the minimum amount of processing to get the smoothest line. The sub-sampling has the biggest effect on the stepping but aslo the biggest effect on the processing effort.

At 10/17 the contours have lost the stepping and even as straight polylines look like the terrain they depict.

5m 50m idx interval 10/17

With the sampling settings taking up the smoothing the straight polylines work well. The nature of contours is such that the nesting of curves, the pinching of incised features and the moiree effect of lines on convex and concave slopes lead the eye to read the surface as a tactile object. TheoContour generates the lines as polylines so the editing of the lines is not too difficult. Introducing an appropriate  lineweight for the index contour and some sensible colours by layer gets the model behaving cartographically:

5m interval index at 50m

With patience a 2m interval is possible:

2m interval 10m index 10/17

Of course the contours are true 3d enitites:

As you would expect the polylines sit at their correct Zs

2m interval 10m index 10/17

Download TheoContour for Bricscad here.

Dowload TheoContour  (as part of the TheoLt Suite)  for AutoCAD here.

TheoContour: Fast Contouring made easy!

You can spend a lot of money on contouring, the software tools for surface interpolation and depiction do not come cheap and even the ‘inbuilt’ AutoDesk options require a hefty investment in a ‘Map 3D’ or ‘Civil’ variant. But there is a very effective and low cost option which I have been using for some time now and it’s proved itself to be a good ‘fast and dirty’ fix for getting contours done: TheoContour.

Like all of the Latimer CAD family of tools this is based on the premise of solving a CAD problem, not a surveying one: there are no data tables to code, no CoGo computations to step over and the outputs are pure CAD entities ready for your next DWG based task. And of course all is in 3D from the start.

Let’s start by looking at the results:

This composite view gives you an idea of what TheContour is capable of: annotated smooth 3D ploylines and shaded surface generation.

So how does it work?

TheoContour is an arx/brx application:

it works with points so getting started is easy: just get your points into AutoCAD! The points can be layered anyway you choose, and obviously, they need to be congruent in terms of height consistency ( in other words they have to be organised such that the Z values are correct!)

Once we are happy all the points are in the current view in WCS the 1st TheoContour command is : theocollate which loads up the points and reports on the surface they describe ready for the next step:

I kid you not, the arx processes this stuff pretty quickly 2,703 points in about 3 s!

Note that the command line report relays the settings we are using on this model. They can be changed easily; I’m not happy with contours at 4 to the metre indexed on the metre so I go to settings and switch the index interval to 5:

I’m now ready to contour:

The command is, you guessed it: theoContour! Plotting the contours takes a little time, this example takes about 45s to generate. Some models can take a while, it’s all dependent on how fine the contours are combined the entity type being generated (lines, polylines or splined polylines).

Not bad for a 1st pass, I would return to the settings and look at smoothing but this gives you a good idea of how simple the process is: and it’s flexible- in effect the datum is the zero value for Z in the current UCS so you can use theocontour to generate contoured surfaces indexed to any plane defined by a UCS! The contours are 2D ploylines in 3D space so they can be edited easily using PEDIT to get them tidy!

So just using 2 commands and tweaking the settings I have got working contours in minutes.

TheoContour also generates profiles and shaded surfaces, the text annotation is pretty neat too but for now I just want to show how simple contouring CAN be if you use TheoContour!

TheoContour for BricsCAD

TheoContour can be downloaded as part of TheoLt core at:…