according to this thread

https://ar.qualcomm.at/arforums/showthread.php?t=834&highlight=image+plane

i deleted the teapot header and replaced it with plane header and included it instead of teapot in plane!! and still teapot appear instead of the blank plane !!

 // Did we find any trackables this frame?
    for(int tIdx = 0; tIdx < state.getNumActiveTrackables(); tIdx++)
    {
        // Get the trackable:
        const QCAR::Trackable* trackable = state.getActiveTrackable(tIdx);
        QCAR::Matrix44F modelViewMatrix =
            QCAR::Tool::convertPose2GLMatrix(trackable->getPose());        

        // Choose the texture based on the target name:
        //int textureIndex = (!strcmp(trackable->getName(), "stones")) ? 0 : 1;
        //const Texture* const thisTexture = textures[textureIndex];
        const Texture* const imgTexture = textures[2];
#ifdef USE_OPENGL_ES_1_1
        // Load projection matrix:
        glMatrixMode(GL_PROJECTION);
        glLoadMatrixf(projectionMatrix.data);

        // Load model view matrix:
        glMatrixMode(GL_MODELVIEW);
        glLoadMatrixf(modelViewMatrix.data);
        glTranslatef(0.f, 0.f, kObjectScale);
        glScalef(kObjectScale, kObjectScale, kObjectScale);

        // Draw object:
        glBindTexture(GL_TEXTURE_2D, thisTexture->mTextureID);
        glTexCoordPointer(2, GL_FLOAT, 0, (const GLvoid*) &teapotTexCoords[0]);
        glVertexPointer(3, GL_FLOAT, 0, (const GLvoid*) &teapotVertices[0]);
        glNormalPointer(GL_FLOAT, 0,  (const GLvoid*) &teapotNormals[0]);
        glDrawElements(GL_TRIANGLES, NUM_TEAPOT_OBJECT_INDEX, GL_UNSIGNED_SHORT,
                       (const GLvoid*) &teapotIndices[0]);
#else

        QCAR::Matrix44F modelViewProjection;

        SampleUtils::translatePoseMatrix(0.0f, 0.0f, kObjectScale,
                                         &modelViewMatrix.data[0]);
        SampleUtils::scalePoseMatrix(target_size.data[0], target_size.data[1], 1.0f,
                                     &modelViewMatrix.data[0]);
        SampleUtils::multiplyMatrix(&projectionMatrix.data[0],
                                    &modelViewMatrix.data[0] ,
                                    &modelViewProjection.data[0]);

        glUseProgram(shaderProgramID);
         
        glVertexAttribPointer(vertexHandle, 3, GL_FLOAT, GL_FALSE, 0,
                              (const GLvoid*) &planeVertices[0]);
        glVertexAttribPointer(normalHandle, 3, GL_FLOAT, GL_FALSE, 0,
                              (const GLvoid*) &planeNormals[0]);
        glVertexAttribPointer(textureCoordHandle, 2, GL_FLOAT, GL_FALSE, 0,
                              (const GLvoid*) &planeTexCoords[0]);
        
        glEnableVertexAttribArray(vertexHandle);
        glEnableVertexAttribArray(normalHandle);
        glEnableVertexAttribArray(textureCoordHandle);
        
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, imgTexture->mTextureID);
        glUniformMatrix4fv(mvpMatrixHandle, 1, GL_FALSE,
                           (GLfloat*)&modelViewProjection.data[0] );
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT,
                       (const GLvoid*) &planeIndices[0]);

        SampleUtils::checkGlError("ImageTargets renderFrame");