microimages - t editing tinlesson we will select name and georeference values. for this exercise,...

Tutorial

Editing TINGeodata

in

TNTmips®

and TNTedit™

EDIT

TIN

Editing TIN Geodata

Before Getting Started

It may be difficult to identify the important points in some illustrations withouta color copy of this booklet. You can print or read this booklet in color fromMicroImages’ web site. The web site is also your source for the newesttutorial booklets on other topics. You can download an installation guide,sample data, and the latest version of TNTlite:

http://www.microimages.com

This booklet introduces techniques for creating, altering, and updating TINgeospatial objects in the powerful Spatial Data Editor in TNTmips® and TNTedit™.TIN objects that you make or import contain node, edge, and triangle elementsthat define a 3D surface. Each element may have associated attributes and can beconnected with complex databases. The exercises in this booklet introduce youto the basic editing tools for TIN elements. The Spatial Data Editor also has toolsfor editing your vector, raster, database, and CAD geodata.

Prerequisite Skills This booklet assumes that you have completed the exercisesin the Displaying Geospatial Data and Navigating tutorials. Those exercisesintroduce essential skills and basic techniques that are not covered again here.Please consult those booklets and the TNTmips reference manual for review.Also, Editing Vector Geodata is recommended, since many editing operationsare the same.

Sample Data The exercises presented in this booklet use sample data that isdistributed with the TNT products. If you do not have access to a TNT productsCD, you can download the data from MicroImages’ web site. In particular, thisbooklet uses objects in the TINLITE Project File in the SF_DATA data collection. Makea read-write copy of that file on your hard drive; you may encounter problems ifyou work directly with the sample data on the CD-ROM.

More Documentation This booklet is intended only as an introduction to TINediting in the Spatial Data Editor. Consult the TNT reference manual, which in-cludes over 200 pages on the Spatial Data Editor, for more information.

TNTmips and TNTlite® TNTmips comes in two versions: the professional ver-sion and the free TNTlite version. This booklet refers to both versions as“TNTmips.” If you did not purchase the professional version (which requires asoftware license key), TNTmips operates in TNTlite mode, which limits objectsize.

The Spatial Data Editor is not available in TNTview or TNTatlas. All the exercisescan be completed in TNTlite using the sample geodata provided.

Keith Ghormley, 21 April 2005

Editing TIN Geodata

The TNT Spatial Data Editor (Edit / Spatia Data)offers a flexible, editing environment that can be usedfor simple one-object tasks or complex multi-layer,multi-object manipulations. You can have a singleobject in one layer, or a combination of read-onlyreference layers with other editable layers. You canhave multiple types of objects open at the same time,stacked in any front-to-back order.

Editing operations apply to the currently “active”layer. As you switch from layer to layer, the edit-ing tools automatically change according to the datatype of the active layer (raster, vector, CAD, or TIN).

The Spatial Data Editor

You may see editing tools like those in TNT in othersoftware products, but the important advantage ofthe TNT Spatial Data Editor is the way you can editmultiple geospatially related objects of differenttypes easily and intuitively. You can concurrentlyedit project materials of all types while TNT auto-matically retains and reconciles their map registra-tions. This means that all the new objects you cre-ate can automatically derive their map registrationfrom other layers, so all of your project materialshave a correct geospatial relationship.

The editor handles multipleraster, vector, CAD, and TINobjects concurrently.

The georeferencecontrol in each object isautomatically recon-ciled to relate itcorrectly to thegeoreference in theother layers.

As you switchbetween layers, theeditor automatically

opens theappropriate tool

palette for the datatype of the current

layer.

The exercises on pages 4 -10 introduce basic editingtechniques for TIN elements.Pages 11-14 present differentways to use referenceobjects, including 3Dperspective and stereo 3Dviews.

A TIN (“Triangulated IrregularNetwork”) is a set ofirregularly spaced three-dimensional nodes thatrepresent a surface as a setof adjacent, conterminoustriangles. Every node is partat least one triangle, andevery triangle satisfies theDelaunay criterion.

Editing TIN Geodata

Understanding TIN Topology

Vocabulary: the hull of aTIN object defines the x-yextents of the object and theshape of the 3D surfacewithin that area. Someediting operations are notsupported outside the hull.For example, in this versionof the Spatial Data Editor,you cannot add new nodesoutside the extents of thehull.

A TIN object is a three-dimensional surface definedby a set of x,y,z coordinate points. The points arejoined by a network of lines such that the lines allact as edges of triangles, and the triangles all meetthe Delaunay criterion. The important thing to re-member is that the edge and triangle elements arecompletely derivative. That is, they are uniquelydetermined by the location of the nodes. Thus youcannot directly edit an edge or triangle in a TINobject. Rather, you will always edit the node ele-ments, and the edges and triangles will be automati-cally adjusted according to the nodes.

TIN objects offer many advantages of speed andefficiency for computer processes that manipulate3D surfaces. You will use TINs for elevation data(for hydrology, watersheds, erosion, surface flow,and orthophoto generation), and for other func-tional surfaces where 3D representations help invisualization and analysis. Thus you can create aTIN object from point observations and take the z

value from any significantstudy variable, such as cropyield, soil contamination,signal strength, or totalevent observations.

The triangle elements in TINobjects are formed by amethod that guaranteesthat the triangles are assmall and equilateral aspossible, given that set ofinput nodes. There isalways one and only oneproper TIN structure thatcan be formed from a givenset of nodes. When youchange one node, theObject Editor automaticallyreconstitutes the localstructure of the TIN.

A node is an x,y,zcoordinate point.

An edgeconnects twonodes.

Every edge belongs toone or two triangles.

Editing TIN Geodata

Create a TIN ObjectStart the TNTmips Spatial Data Editor by selectingSpatial Data from the Edit menu. TNTmips opensthe Spatial Data Editor window and an associatedView window. Click the Create New Object icon but-ton and select TIN from the drop down menu.TNTmips opens a New Object Values dialog.

Accept the default values in the New Object Valuesdialog. In later exercises we will change Name andGeoreference values as we tell the Editor how ournew TIN object relates spatially to other layers. Fornow, click the OK button at the bottom of the dialog.The editor opens a NEWTIN object, opens the TINTools window (described on the next page), and addsa new TIN object to the layer list in the Spatial DataEditor window.

The Spatial Data Editor View 1 window contains aminimal TIN object: 4 nodes, 5 edges, and 2 triangles.The tools in the TIN Tools window are described inthe following exercises.

STEPS start the Spatial DataEditor by selectingSpatial Data from theEdit menu

in the TNTmipsSpatial Data Editorwindow, click CreateNew Object and selectTIN from the drop downmenu

observe that the Namefield says NEWTIN and thedefault georeference isUser Defined

click [OK] to complete thenew object setup

The New Object Valueswindow opens when youselect TIN from the CreateNew Object icon button inthe Spatial Data Editorwindow. In a subsequentlesson we will select Nameand Georeference values.For this exercise, click the[OK] push-button to acceptthe default name (“NEWTIN”)and georeference (“UserDefined.”).

Editing TIN Geodata

The tool palette in the TIN Tools window of-fers three tools: Add Node, Add Line, and Edit.If you have used the tool palettes that the Spa-tial Data Editor presents for other object types(raster, vector, and CAD), you are familiar with

a wider variety of editing tools: such as add poly-gon. But remember that the edges and triangles inTIN objects are strictly functions of the node ele-ments and so they have no existence apart fromnodes. Thus when you add a node, you automati-cally add connecting edges and you automaticallytrigger a reconstitution of all local triangles. Youcannot add triangles directly, but you can add lines,which the editor immediately incoporates as edgesin new triangles.

Click the Add Node tool button in the TIN Toolswindow. Then position the mouse cursor in theSpatial View window and click the left mouse but-ton to place the crosshair tool. The crosshairmarks the position of the new node. You can dragand reposition the crosshair with the left mousebutton, and then add your new node by clickingthe right mouse button.

The TIN Tools Palette

STEPSclick the Add Nodetoolclick the left mousebutton in the Spatial Viewwindow to position thecrosshair toolclick the right mousebutton to add a new nodeat the crosshair location

Place the crosshair tool with theleft mouse button. Then add thenew node by clicking the rightmouse button

As soon as youadd a new node,the Editorreconstitutes theTIN and redisplaysthe new topology.

The Point Edit Controls window shows thecoordinates of the crosshair tool.

Add Node

Editing TIN Geodata

After adding several morenodes, the NEWTIN objectshows a more complextopology. Use the Point EditControls dialog to assign anelevation value to new nodesbefore you add them.

After adding one node, the NEWTIN object has 5nodes, 8 edges, and 4 triangles (refer to the illustra-tion on the previous page). Apply the Add Nodetool several more times to add nodes across the ob-ject. Observe that after you add each node with theright mouse button, the Editor reconstitutes the TINobject and redisplays the new topology. Observealso that you cannot add nodes outside the extentsof the existing hull area

Since TIN objects are designed to represent 3D sur-faces, each node has a z-coordinate value. The de-fault z value is zero, but you can type in an actualelevation value before you add a new node in thePoint Edit Controls dialog. Position the crosshair,type in the z value, and then click the right mousebutton to add the 3D node. Elevation values can bepositive or negative, including decimal values.

The standard View window display tools are all avail-able as you add nodes. Use the zoom and pan toolsto try different viewpoints as you add nodes.

Adding Node Elements

STEPSadd several new nodesmake sure the ManualEntry checkbox isselectedtype in z coordinatevalues for some newnodes in the Point EditControls dialog

Editing TIN Geodata

When you select the Edit tool fromthe TIN Tools palette, the SpatialData Editor opens the EditElements dialog. Click the EditElement icon button.

In this exercise we will switch to the editingmode in order to go back to some of the nodesyou added to the NEWTIN object and modifythem. First, select the Edit tool in the TIN Toolspalette. The Spatial Data Editor closes the Point

Edit Controls window that you used for addingnodes, and opens the Element Selection window.

In this exercise we want to select and modify nodeelements only, so turn off selection for edge andtriangle elements. Click the Show Details icon but-ton in the object list in the Spatial Data Editor win-dow to expose the element control rows. Then clickthe select icon button on the edge and triangle rowsto turn off selection for those elements. (When theSelect icon is blue, selection is enabled; when it isred, selection is disabled.)

Click the Edit Element tool in the Operation panel ofthe Edit Elements dialog. In the next exercise we willuse this tool to select node elements and changetheir x, y, and z coordinate values.

The Editing Mode

STEPSclick the EditElements tool in theTIN Tools paletteclick the ShowDetails icon button inthe TNTmips SpatialData Editor window toexpose the elementselection rowsclick the Select iconbutton in the edgeand triangle rows toturn off selection forthose elementsclick the Edit Elementtool in the Operationpanel of the ElementSelection window

Turn off the selection icons for node and triangleelements.

Expose the element control rows in the SpatialData Editor window.

Editing TIN Geodata

Click on a node element in the View window. Theelement becomes active and is displayed in the ac-tive highlight color. (You can change active andselected colors with Options / Colors in the Viewwindow; you can change node, edge, and trianglecolors with Layer / Controls in the Spatial Data Edi-tor window.)

Click the right mouse button to activate the selectednode for editing. The Editor puts the crosshair toolon the selected node and opens the associated PointEdit Controls dialog. Use the left mouse button todrag the crosshair tool, and click the right mousebutton to apply the change. When a node is activefor editing, you can also change the z coordinatevalue in the Point Edit Controls dialog.

The Delete operation is similar. Select the DeleteElement icon button in the Operation panel of theEdit Elements dialog. Select a node element to de-lete with the left mouse button. Apply the deleteoperation with the right mouse button.

Every time you move or delete a node element, theEditor reconstitutes the TIN object.

Move and Delete Nodes

STEPSclick the left mousebutton on a node elementto select itclick the right mousebutton to open the PointEdit Controls window forthe selected nodedrag the crosshair tool ortype in new coordinatevaluesclick the right mousebutton to apply the editsselect the DeleteElement icon in theOperation panelclick the left mousebutton to select a node todeleteclick the right mousebutton to apply the deleteoperation

When you click the right mousebutton for a selected node, thePoint Edit Controls dialog opensand the crosshair tool appearsin the View window.

Editing TIN Geodata

You can change the z value for each node elementas in the previous exercise by selecting it and open-ing its associated Point Edit Controls dialog. Aquicker way to traverse all the nodes in your TINobject is to select the Z Value tool in the Operationpanel of the Edit Elements dialog. The Z Value toolopens a drop down panel in the Edit Elements dia-log where you can type in the z value for a selectednode element directly. This one-step z value edit-ing is easier than the two-step method presented inthe previous exercise, but it does not offer thecrosshair tool or any coordinate fields for the x,ycoordinate values. Thus, if you want to changemore than the z value for a node, use the Point EditControls method. But if you want to review andmodify z values only, use the Z Value tool.

Click the Z Value tool in the Edit Elements dialog.Select one of the node elements in the View win-dow. Click on the Z Value field in the Edit Elementsdialog and type in a new z value.

Quick Z Value Traversal

STEPSclick the Z Value toolin the Edit Elementsdialogselect a node element inthe View windowtype in a new Z Value inthe drop down panel inthe Edit Elements dialog

When you click the ZValue tool in theOperation panel, a dropdown panel opens andlets you change the ZValue and Z Scale forthe selected nodeelement.

NOTE on the Delete tool: This booklet does not treat the use of the Delete toolexcept with node elements. It is possible to delete edge and (depending on the

local topology) triangle elements, but such an operation is useful only in rare circum-stances. If you delete an edge element, you create a hole in the TIN hull where youcannot add or move further node elements.

After this exercise, youdo not need the NEWTIN

object we have been using.Click the Remove iconbutton in the NEWTIN row inthe Spatial Data Editorwindow. TNT asks if youwant to save your changesor discard them. Since wehave no further use for thispractice object, you candiscard it.

Editing TIN Geodata

The TNT Spatial Data Editor proves its real useful-ness when you use multiple layers in the View win-dow. You can edit a TIN layer using one or morereference layers for information and control. In thisexercise we will use an extracted piece of a USGStopo sheet to compare and adjust z values for nodeelements. You could also use ToolTips to read zvalues from an elevation raster object, or an airphotoas a reference for tracing break lines (see page 15).

First add the HAYWARD1 raster object from the TINLITE

Project File in the SF_LITE folder. This downsampledextract from the full Hayward topo sheet will providevisual reference for elevation values. Open theTINLITE TIN object in the same folder for editing. ThisTIN object was generated by the DEM extractionprocess from a pair of stereo airphotos. Use the ZValue tool (see the previous exercise) to comparethe derived z values of the nodes to the elevationvalues printed on the topo map.

Use a Reference LayerSTEPS

click Add Layer inthe Spatial DataEditor window and selectSF_DATA / TINLITE / HAYWARD1click Open Objectfor Editing in theEditor window and selectSF_DATA / TINLITE / TINLITE

select the EditElements tool in theTIN Tools paletteuse the Z Value toolto compare zvalues of node elementsto the contour values inthe reference layer

Using a reference layer behind your TIN object lets youcompare and correct elements. The printed elevationvalues on a topo map can be used to check the z valuesof node elements. Read theelevation contours, select a node,and adjust its z value.

The HAYWARD1 topo sheetused in this example wasresampled for illustrationpurposes to fit TNTlite sizeconstraints. The resultinglow resolution would makeextended use of thisreference object tedious.

Editing TIN Geodata

You can open a 3D perspective viewin the Display Spatial Dataprocess (below) to view the TINobject that you are editing (left).

At the same time that you are using the Spatial DataEditor to modify a TIN object, you can use the TNTDisplay process to view the TIN in 3D perspective.You can have both processes open at the same timeand use the 3D perspective view in the Display pro-cess to identify features in the TIN object that youwant to modify. For example, a TIN surface gener-ated from stereo airphotos may have “posts andholes” that you want to bring into conformity withthe surrounding surface.

Be aware that the Spatial Data Editor keeps thechanges you make to a TIN object in temporary stor-age so that you can decide at the end of a sessionwhether to keep or discard your edits. Therefore,the changes you make are not immediately availableto the 3D Perspective view in the Display process.(A future version of the process may offer a 3Dperspective view as part of the Spatial Data Editor.)

If you need review, refer to the tutorial booklet 3DPerspective Visualization.

Examine Your TIN in 3D Perspective

STEPSremove the HAYWARD1reference layer from theprevious exercise byclicking its Remove iconbutton in the layer listopen the TNT Displayprocess (Display /Spatial Data)open a new 3DGroupclick the Add TINicon button andselect TINLITE from theTINLITE Project Fileuse the 3D perspectiveviewpoint tools toexamine the TIN and lookfor node elements youmay want to edit

Editing TIN Geodata

An even more powerful editing trick lets you viewa stereo 3D reference image while you edit a TINobject. Note: this exercise requires you to use thetechnique of “cross-eyed stereo” viewing (describedin the turtorial 3D Perspective Visualization), whichis difficult for some people. A future version of theEditor will add direct support for other stereo 3Dmethods of viewing reference images.

As in the previous exercise, use the TNT displayprocess to open a 2D view alongside the Editor’sView window. As illustrated below, add the TINLITE /LEFTLITE airphoto to the Display process window onthe left, and add the TINLITE / RIGHTLITE airphoto as areference layer in the Editor’s View window on theright. When the windows are sized and positionedas illustrated, you should be able to see a stereo 3Dimage by using the cross-eyed stereo technique.You may need to change the drawing style of theTIN layer or hide it temporarily if it interferes withthe stereo 3D effect. You can use such stereo 3Dreference information to edit break lines in the TINto conform to ridge and drainage features.

Use a Stereo 3D Reference ImageSTEPS

close the 3D perspectiveview in the Displayprocess from theprevious exerciseopen a new 2DGroup in theDisplay processclick the Add Layericon button for theDisplay process andselect SF_DATA / TINLITE /LEFTLITE

click the Add Layericon button for theEditor and select RIGHTLITE

from the TINLITE ProjectFileresize and position thewindows as illustratedadjust the display toachieve stereo 3D cross-eyed effect, hiding theTIN layer temporarily ifnecessary

The cross-eyed stereo visualization technique isdescribed in the tutuorial 3D Perspective Visualization.

Editing TIN Geodata

In addition to the standard attribute tables(below), you can view Active ElementInformation in a drop down panel in theSpatial Data Editor window.

Node, edge, and triangle elements can have anynumber of related attribute tables associated withthem just as elements in CAD and vector objectscan. (Refer to the tutorial Editing Geospatial Vec-tors). The special properties of TIN elements canbe especially useful in query and analysis opera-tions. To generate the standard attributes for a TINobject, select Update Standard Attributes from theTools icon menu in the Spatial Data Editor window.To view the tables, click the Show Tables icon but-ton associated with each element type. Then clickthe View Table icon to open a database view win-dow for each table you want to see.

In the illustration below, a triangle element has beenselected in the View window, and both the ActiveElement Information and the associated record from

the TRIANGLESTATS table are exposed.

Working with TIN AttributesSTEPS

exit the Display processused in the previousexerciseselect UpdateStandard Attributesfrom the TINLITE Toolsicon menu in the SpatialData Editor windowclick the ShowTables icon buttonfor edges and trianglesclick the View Tableicon button for theTRIANGLESTATS table listedfor the triangle elementsclick on a triangleelement in the SpatialView window

Editing TIN Geodata

Drawing Break LinesIt is best to think of a TIN object as a set of 3D nodesfrom which a network of edges and triangles aregenerated. The nodes determine the edges and tri-angles. The edges and triangles are derived fromthe nodes. Thus, the most natural way to edit a TINobject is to work with node elements, and let theEditor manage the edge and triangle network.

The Spatial Data Editor also allows you to perform alimited number of editing operations on edge ele-ments. Drawing edge elements directly lets you tracebreak lines in an elevation surface so that the TIN’sridges and valleys will strictly conform to the actualsurface.

You can add edge elements by drawing with the stan-dard line tool. The Editor breaks your new line intodiscrete edge segments by adding nodes where theline changes directions, and then it reconstitutesthe TIN topography in the local area.

You can delete edge elements by selecting them andapplying the Editor’s delete operation, but note thatdeleting an edge creates a hole in the TIN hull andyou cannot thereafter add node or edges in the hole.

You cannot reshape edge elements.

STEPScreate a new TINobjectselect the Add Edgetool in the TIN Toolspaletteuse the standard linedrawing techniques inthe stretch mode todraw a complex breaklineclick the right mousebutton to add the breaklineexamine the newlyreconstituted TINstructure

Below left: use the line toolto draw a break line.Below right: The Editoradds node elements alongthe breakline and reconsti-tutes the TIN topography.

Advanced Software for Geospatial AnalysisEDIT

TIN

Voice: (402)477-9554www.microimages.com

MicroImages, Inc. publishes a complete line of professional software for advancedgeospatial data visualization, analysis, and publishing. Contact us or visit our web site fordetailed product information.TNTmips TNTmips is a professional system for fully integrated GIS, image analysis,

CAD, TIN, desktop cartography, and geospatial database management.TNTedit TNTedit provides interactive tools to create, georeference, and edit vector, image,

CAD, TIN, and relational database project materials in a wide variety of formats.TNTview TNTview has the same powerful display features as TNTmips and is perfect for

those who do not need the technical processing and preparation features of TNTmips.TNTatlas TNTatlas lets you publish and distribute your spatial project materials on CD-

ROM at low cost. TNTatlas CDs can be used on any popular computing platform.TNTserver TNTserver lets you publish TNTatlases on the Internet or on your intranet.

Navigate through geodata atlases with your web browser and the TNTclient Java applet.TNTlite TNTlite is a free version of TNTmips for students and professionals with small

projects. You can download TNTlite from MicroImages’ web site, or you can orderTNTlite on CD-ROM.

3D perspective ................................. 12Add Node tool .................................... 6attribute tables .................................. 14break lines ................................... 13, 15crosshair tool ...................................... 6Delaunay criterion .......................... 3, 4delete nodes ........................................ 9edge ..................................................... 4edit element tool ................................. 8Edit Elements dialog ........................... 8editing mode ........................................ 8hull ...................................................... 4move nodes ......................................... 9New Object Values dialog ................... 5node .................................................... 4Point Edit Controls dialog .............. 6, 7

Indexposts and holes ................................. 12prerequisite tutorials ........................... 2reference layer ................................... 11sample data ......................................... 2Spatial Data Editor ............................. 3standard attributes ............................ 14stereo 3D .......................................... 13TIN attributes ................................... 14TNTlite ............................................... 2Tools Palette ....................................... 6topology ............................................. 4triangles ............................................... 4z coordinate values ................... 7, 9, 10Z Scale .............................................. 10Z Value tool ...................................... 10

microimages - t editing tinlesson we will select name and georeference values. for this exercise,...

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